Method of treating pain utilizing controlled release oxymorphone pharmaceutical compositions and instruction on dosing for renal impairment

ABSTRACT

The invention pertains to a method of using oxymorphone in the treatment of pain by providing a patient with an oxymorphone dosage form and informing the patient or prescribing physician that the bioavailability of oxymorphone is increased in patients with renal impairment.

BACKGROUND OF THE INVENTION

Pain is the most frequently reported symptom and it is a common clinicalproblem which confronts the clinician. Many millions of people in theUSA suffer from severe pain that, according to numerous recent reports,is chronically undertreated or inappropriately managed. The clinicalusefulness of the analgesic properties of opioids has been recognizedfor centuries, and morphine and its derivatives have been widelyemployed for analgesia for decades in a variety of clinical pain states.

Oxymorphone HCl (14-hydroxydihydromorphinone hydrochloride) is asemi-synthetic phenanthrene-derivative opioid agonist, widely used inthe treatment of acute and chronic pain, with analgesic efficacycomparable to other opioid analgesics. Oxymorphone is currently marketedas an injection (1 mg/ml in 1 ml ampules; 1.5 mg/ml in 1 ml ampules; 1.5mg/ml in 10 ml multiple dose vials) for intramuscular, subcutaneous, andintravenous administration, and as 5 mg rectal suppositories. At onetime, 2 mg, 5 mg and 10 mg oral immediate release (IR) tabletformulations of oxymorphone HCl were marketed. Oxymorphone HCl ismetabolized principally in the liver and undergoes conjugation withglucuronic acid and reduction to 6-alpha- and beta-hydroxy epimers.

An important goal of analgesic therapy is to achieve continuous reliefof chronic pain. Regular administration of an analgesic is generallyrequired to ensure that the next dose is given before the effects of theprevious dose have worn off. Compliance with opioids increases as therequired dosing frequency decreases. Non-compliance results insuboptimal pain control and poor quality of life outcomes. (Ferrell B etal. Effects of controlled-release morphine on quality of life for cancerpain. Oncol. Nur. Forum 1989; 4:521-26). Scheduled, rather than “asneeded” administration of opioids is currently recommended in guidelinesfor their use in chronic non-malignant pain. Unfortunately, evidencefrom prior clinical trials and clinical experience suggests that theshort duration of action of immediate release oxymorphone wouldnecessitate administration every 4-6 hours in order to maintain optimallevels of analgesia in chronic pain. A controlled release formulationwhich would allow less frequent dosing of oxymorphone would be useful inpain management.

For instance, a controlled release formulation of morphine has beendemonstrated to provide patients fewer interruptions in sleep, reduceddependence on caregivers, improved compliance, enhanced quality of lifeoutcomes, and increased control over the management of pain. Inaddition, the controlled release formulation of morphine was reported toprovide more constant plasma concentration and clinical effects, lessfrequent peak to trough fluctuations, reduced dosing frequency, andpossibly fewer side effects. (Thirlwell M P et al., Pharmacokinetics andclinical efficacy of oral morphine solution and controlled-releasemorphine tablets in cancer patients. Cancer 1989; 63:2275-83; GoughnourB R et al., Analgesic response to single and multiple doses ofcontrolled-release morphine tablets and morphine oral solution in cancerpatients. Cancer 1989; 63:2294-97; Ferrell B. et al., Effects ofcontrolled-release morphine on quality of life for cancer pain. Oncol.Nur. Forum 1989; 4:521-26.

There are two factors associated with the metabolism of some drugs thatmay present problems for their use in controlled release systems. One isthe ability of the drug to induce or inhibit enzyme synthesis, which mayresult in a fluctuating drug blood plasma level with chronic dosing. Theother is a fluctuating drug blood level due to intestinal (or othertissue) metabolism or through a hepatic first-pass effect.

Oxymorphone is metabolized principally in the liver, resulting in anoral bioavailability of about 10%. Evidence from clinical experiencesuggests that the short duration of action of immediate releaseoxymorphone necessitates a four hour dosing schedule to maintain optimallevels of analgesia. It would be useful to clinicians and patients aliketo have controlled release dosage forms of oxymorphone to use to treatpain and a method of treating pain using the dosage forms.

Diseases of the kidney can cause impaired kidney function. Chronic renalfailure in particular can be caused by any number of sources, includingdiabetes and high blood pressure, which are two of the most commoncauses according to the National Kidney Foundation. Impaired kidneyfunction results in a potential build up of substances that aretypically filtered out by the kidneys, such as waste products as well assome drugs.

SUMMARY OF THE INVENTION

One aspect of the invention is a method of using oxymorphone in thetreatment of pain comprising providing a patient with a therapeuticallyeffective amount of oxymorphone and informing the patient or thepatient's prescribing physician that the bioavailability of oxymorphoneis increased in patients with renal impairment.

Another aspect of the invention provides a method of using oxymorphonein the treatment of pain in a patient having renal impairment in needthereof comprising providing a patient having renal impairment with atherapeutically effective amount of an oral dosage form of oxymorphone,informing the patient or the patient's prescribing physician that thebioavailability of oxymorphone is increased in patients with renalimpairment, and orally administering the dosage form of oxymorphone tothe patient.

A further aspect of the invention provides a method of using oxymorphonein the treatment of pain in a patient having moderate or severe renalimpairment in need thereof comprising providing a patient havingmoderate or severe renal impairment with a therapeutically effectiveamount of a controlled release oral dosage form of oxymorphone,informing the patient or the patient's prescribing physician that thebioavailability of oxymorphone is increased in patients with renalimpairment, and orally administering the composition to the patient,wherein the log transformed AUC of oxymorphone is about 1.05 to about2.45 times greater than the log transformed AUC of a healthy patient ifthe healthy patient were to be administered the same dose.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a pharmacokinetic profile for 6-hydroxy oxymorphone with PIDscores.

FIG. 2 is a pharmacokinetic profile for oxymorphone with PID scores.

FIG. 3 is a pharmacokinetic profile for 6-hydroxy oxymorphone withcategorical pain scores.

FIG. 4 is a pharmacokinetic profile for oxymorphone with categoricalpain scores.

FIG. 5 is a graph of the mean blood plasma concentration of oxymorphoneversus time for clinical study 1.

FIG. 6 is a graph of the mean blood plasma concentration of oxymorphoneversus time for clinical study 2.

FIG. 7 is a graph of the mean blood plasma concentration of oxymorphoneversus time for clinical study 3.

FIG. 8 is a graph of the mean blood plasma concentration of 6-hydroxyoxymorphone versus time for clinical study 3.

FIG. 9 is a graph of the mean blood plasma concentration of oxymorphonefor immediate and controlled release tablets from a single dose study.

FIG. 10 is a graph of the mean blood plasma concentration of oxymorphonefor immediate and controlled release tablets from a steady state study.

FIG. 11 is a graph of the mean plasma concentration of oxymorphone,6-OH-oxymorphone, and oxymorphone-3-glucuronide.

FIG. 12 is a graph of the ratio and 90% confidence limits for comparisonof renally impaired to healthy controls (ln-transformed results).

FIG. 13 is a graph of the mean (SD) plasma metabolite-to-parent ratios.

FIG. 14 is a graph of the mean urinary excretion rate (nmol/hr) ofoxymorphone and metabolites.

FIG. 15 is a graph of the cumulative urinary excretion of oxymorphoneand metabolites (percent of administered dose).

FIG. 16 is a graph of the relationship between AUC and creatinineclearance.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides methods using oxymorphone in thetreatment of pain. In one aspect of the invention the method may involvesteps of providing a patient with a therapeutically effective amount ofoxymorphone and informing the patient or the patient's prescribingphysician that the bioavailability of oxymorphone is increased inpatients with renal impairment.

Among the controlled (or extended) release, as well as immediaterelease, pharmaceutical compounds comprising oxymorphone that may beused in the methods of this invention is Opana®, which upon its approvalon Jun. 22, 2006 became the first-ever controlled release oxymorphoneformulation to be approved by the United States Food and DrugAdministration (FDA). Opana® is available in both immediate release andcontrolled or extended release dosage forms. The approved labels ofOpana® are incorporated herein by reference to the extent permitted bylaw.

The present invention also provides methods for alleviating pain for 12to 24 hours using a single dose of a pharmaceutical composition byproducing a blood plasma level of oxymorphone and/or 6-OH oxymorphone ofat least a minimum value for at least 12 hours or more. As used herein,the terms “6-OH oxymorphone” and “6-hydroxy oxymorphone” areinterchangeable and refer to the analog of oxymorphone having an alcohol(hydroxy) moiety that replaces the carboxy moiety found on oxymorphoneat the 6-position.

To overcome the difficulties associated with a 4-6 hourly dosingfrequency of oxymorphone, this invention provides an oxymorphonecontrolled release oral solid dosage form, comprising a therapeuticallyeffective amount of oxymorphone or a pharmaceutically acceptable salt ofoxymorphone. It has been found that the decreased rate of release ofoxymorphone from the oral controlled release formulation of thisinvention does not substantially decrease the bioavailability of thedrug as compared to the same dose of a solution of oxymorphoneadministered orally. The bioavailability is sufficiently high and therelease rate is such that a sufficient plasma level of oxymorphoneand/or 6-OH oxymorphone is maintained to allow the controlled releasedosage to be used to treat patients suffering moderate to severe painwith once or twice daily dosing. The dosing form of the presentinvention can also be used with thrice daily dosing.

It is critical when considering the present invention that thedifference between a controlled release tablet and an immediate releaseformulation be fully understood. In classical terms, an immediaterelease formulation releases at least 80% of its active pharmaceuticalingredient within 30 minutes. With reference to the present invention,the definition of an immediate release formulation will be broadenedfurther to include a formulation which releases more than about 80% ofits active pharmaceutical ingredient within 60 minutes in a standard USPPaddle Method dissolution test at 50 rpm in 500 ml media having a pH ofbetween 1.2 and 6.8 at 37° C. “Controlled release” formulations, asreferred to herein, will then encompass any formulations which releaseno more than about 80% of their active pharmaceutical ingredients within60 minutes under the same conditions.

The controlled release dosage form of this invention exhibits adissolution rate in vitro, when measured by USP Paddle Method at 50 rpmin 500 ml media having a pH between 1.2 and 6.8 at 37° C., of about 15%to about 50% by weight oxymorphone released after 1 hour, about 45% toabout 80% by weight oxymorphone released after 4 hours, and at leastabout 80% by weight oxymorphone released after 10 hours.

When administered orally to humans, an effective controlled releasedosage form of oxymorphone should exhibit the following in vivocharacteristics: (a) peak plasma level of oxymorphone occurs withinabout 1 to about 8 hours after administration; (b) peak plasma level of6-OH oxymorphone occurs within about 1 to about 8 hours afteradministration; (c) duration of analgesic effect is through about 8 toabout 24 hours after administration; (d) relative oxymorphonebioavailability is in the range of about 0.5 to about 1.5 compared to anorally-administered aqueous solution of oxymorphone; and (e) the ratioof the area under the curve of blood plasma level vs. time for 6-OHoxymorphone compared to oxymorphone is in the range of about 0.5 toabout 1.5. Of course, there is variation of these parameters amongsubjects, depending on the size and weight of the individual subject,the subject's age, individual metabolism differences, and other factors.Indeed, the parameters may vary in an individual from day to day.Accordingly, the parameters set forth above are intended to be meanvalues from a sufficiently large study so as to minimize the effect ofindividual variation in arriving at the values. A convenient method forarriving at such values is by conducting a study in accordance withstandard FDA procedures such as those employed in producing results foruse in a new drug application (or abbreviated new drug application)before the FDA. Any reference to mean values herein, in conjunction withdesired results, refer to results from such a study, or some comparablestudy. Reference to mean values reported herein for studies actuallyconducted are arrived at using standard statistical methods as would beemployed by one skilled in the art of pharmaceutical formulation andtesting for regulatory approval.

In one specific embodiment of the controlled release matrix form of theinvention, the oxymorphone or salt of oxymorphone is dispersed in acontrolled release delivery system that comprises a hydrophilic materialwhich, upon exposure to gastrointestinal fluid, forms a gel matrix thatreleases oxymorphone at a controlled rate. The rate of release ofoxymorphone from the matrix depends on the drug's partition coefficientbetween components of the matrix and the aqueous phase within thegastrointestinal tract. In a preferred form of this embodiment, thehydrophilic material of the controlled release delivery system comprisesa mixture of a heteropolysaccharide gum and an agent capable ofcross-linking the heteropolysaccharide in presence of gastrointestinalfluid. The controlled release delivery system may also comprise awater-soluble pharmaceutical diluent mixed with the hydrophilicmaterial. Preferably, the cross-linking agent is a homopolysaccharidegum and the inert pharmaceutical diluent is a monosaccharide, adisaccharide, or a polyhydric alcohol, or a mixture thereof.

In a specific preferred embodiment, the appropriate blood plasma levelsof oxymorphone and 6-hydroxy oxymorphone are achieved using oxymorphonein the form of oxymorphone hydrochloride, wherein the weight ratio ofheteropolysaccharide to homopolysaccharide is in the range of about 1:3to about 3:1, the weight ratio of heteropolysaccharide to diluent is inthe range of about 1:8 to about 8:1, and the weight ratio ofheteropolysaccharide to oxymorphone hydrochloride is in the range ofabout 10:1 to about 1:10. A preferred heteropolysaccharide is xanthangum and a preferred homopolysaccharide is locust bean gum. The dosageform also comprises a cationic cross-linking agent and a hydrophobicpolymer. In the preferred embodiment, the dosage form is a tabletcontaining about 5 mg to about 80 mg of oxymorphone hydrochloride. In amost preferred embodiment, the tablet contains about 20 mg oxymorphonehydrochloride.

The invention includes a method which comprises achieving appropriateblood plasma levels of drug while providing extended pain relief byadministering one to three times per day to a patient suffering moderateto severe, acute or chronic pain, an oxymorphone controlled release oralsolid dosage form of the invention in an amount sufficient to alleviatethe pain for a period of about 8 hours to about 24 hours. This type andintensity of pain is often associated with cancer, autoimmune diseases,infections, surgical and accidental traumas and osteoarthritis.

The invention also includes a method of making an oxymorphone controlledrelease oral solid dosage form of the invention which comprises mixingparticles of oxymorphone or a pharmaceutically acceptable salt ofoxymorphone with granules comprising the controlled release deliverysystem, preferably followed by directly compressing the mixture to formtablets.

Pharmaceutically acceptable salts of oxymorphone which can be used inthis invention include salts with the inorganic and organic acids whichare commonly used to produce nontoxic salts of medicinal agents.Illustrative examples would be those salts formed by mixing oxymorphonewith hydrochloric, sulfuric, nitric, phosphoric, phosphorous,hydrobromic, maleric, malic, ascorbic, citric or tartaric, pamoic,lauric, stearic, palmitic, oleic, myristic, lauryl sulfuric,naphthalenesulfonic, linoleic or linolenic acid, and the like. Thehydrochloride salt is preferred.

It has now been found that 6-OH oxymorphone, which is one of themetabolites of oxymorphone, may play a role in alleviating pain. Whenoxymorphone is ingested, part of the dosage gets into the bloodstream toprovide pain relief, while another part is metabolized to 6-OHoxymorphone. This metabolite then enters the bloodstream to providefurther pain relief. Thus it is believed that both the oxymorphone and6-hydroxyoxymorphone levels are important to pain relief.

The effectiveness of oxymorphone and 6-hydroxyoxymorphone at relievingpain and the pharmacokinetics of a single dose of oxymorphone werestudied. The blood plasma levels of both oxymorphone and6-hydroxyoxymorphone were measured in patients after a single dose ofoxymorphone was administered. Similarly, the pain levels in patientswere measured after a single administration of oxymorphone to determinethe effective duration of pain relief from a single dose. FIGS. 1-2 showthe results of these tests, comparing pain levels to oxymorphone and6-hydroxy oxymorphone levels.

For these tests, pain was measured using a Visual Analog Scale (VAS) ora Categorical Scale. The VAS scales consisted of a horizontal line, 100mm in length. The left-hand end of the scale (0 mm) was marked with thedescriptor “No Pain” and the right-hand end of the scale (100 mm) wasmarked with the descriptor “Extreme Pain”. Patients indicated theirlevel of pain by making a vertical mark on the line. The VAS score wasequal to the distance (in mm) from the left-hand end of the scale to thepatient's mark. For the categorical scale, patients completed thefollowing statement, “My pain at this time is” using the scale None=0,Mild=1, Moderate=2, or Severe=3.

As can be seen from these figures, there is a correlation between painrelief and both oxymorphone and 6-hydroxyoxymorphone levels. As theblood plasma levels of oxymorphone and 6-hydroxyoxymorphone increase,pain decreases (and pain intensity difference and pain reliefincreases). Thus, to the patient, it is the level of oxymorphone and6-hydroxyoxymorphone in the blood plasma which is most important.Further it is these levels which dictate the efficacy of the dosageform. A dosage form which maintains a sufficiently high level ofoxymorphone or 6-hydroxyoxymorphone for a longer period need not beadministered frequently. Such a result is accomplished by embodiments ofthe present invention.

The oxymorphone controlled release oral solid dosage form of thisinvention can be made using any of several different techniques forproducing controlled release oral solid dosage forms of opioidanalgesics.

In one embodiment, a core comprising oxymorphone or oxymorphone salt iscoated with a controlled release film which comprises a water insolublematerial and which upon exposure to gastrointestinal fluid releasesoxymorphone from the core at a controlled rate. In a second embodiment,the oxymorphone or oxymorphone salt is dispersed in a controlled releasedelivery system that comprises a hydrophilic material which uponexposure to gastrointestinal fluid forms a gel matrix that releasesoxymorphone at a controlled rate. A third embodiment is a combination ofthe first two: a controlled release matrix coated with a controlledrelease film. In a fourth embodiment the oxymorphone is incorporatedinto an osmotic pump. In any of these embodiments, the dosage form canbe a tablet, a plurality of granules in a capsule, or other suitableform, and can contain lubricants, colorants, diluents, and otherconventional ingredients.

Osmotic Pump

An osmotic pump comprises a shell defining an interior compartment andhaving an outlet passing through the shell. The interior compartmentcontains the active pharmaceutical ingredient. Generally the activepharmaceutical ingredient is mixed with excipients or other compositionssuch as a polyalkylene. The shell is generally made, at least in part,from a material (such as cellulose acetate) permeable to the liquid ofthe environment where the pump will be used, usually stomach acid. Onceingested, the pump operates when liquid diffuses through the shell ofthe pump. The liquid dissolves the composition to produce a saturatedsituation. As more liquid diffuses into the pump, the saturated solutioncontaining the pharmaceutical is expelled from the pump through theoutlet. This produces a nearly constant release of active ingredient, inthe present case, oxymorphone.

Controlled Release Coating

In this embodiment, a core comprising oxymorphone or oxymorphone salt iscoated with a controlled release film which comprises a water insolublematerial. The film can be applied by spraying an aqueous dispersion ofthe water insoluble material onto the core. Suitable water insolublematerials include alkyl celluloses, acrylic polymers, waxes (alone or inadmixture with fatty alcohols), shellac and zein. The aqueousdispersions of alkyl celluloses and acrylic polymers preferably containa plasticizer such as triethyl citrate, dibutyl phthalate, propyleneglycol, and polyethylene glycol. The film coat can contain awater-soluble material such as polyvinylpyrrolidone (PVP) orhydroxypropylmethylcellulose (HPMC).

The core can be a granule made, for example, by wet granulation of mixedpowders of oxymorphone or oxymorphone salt and a binding agent such asHPMC, or by coating an inert bead with oxymorphone or oxymorphone saltand a binding agent such as HPMC, or by spheronising mixed powders ofoxymorphone or oxymorphone salt and a spheronising agent such asmicrocrystalline cellulose. The core can be a tablet made by compressingsuch granules or by compressing a powder comprising oxymorphone oroxymorphone salt.

The in vitro and in vivo release characteristics of this controlledrelease dosage form can be modified by using mixtures of different waterinsoluble and water soluble materials, using different plasticizers,varying the thickness of the controlled release film, includingrelease-modifying agents in the coating, or by providing passagewaysthrough the coating.

Controlled Release Matrix

It is important in the present invention that appropriate blood plasmalevels of oxymorphone and 6-hydroxy oxymorphone be achieved andmaintained for sufficient time to provide pain relief to a patient for aperiod of 12 to 24 hours. The preferred composition for achieving andmaintaining the proper blood plasma levels is a controlled-releasematrix. In this embodiment, the oxymorphone or oxymorphone salt isdispersed in a controlled release delivery system that comprises ahydrophilic material (gelling agent) which upon exposure togastrointestinal fluid forms a gel matrix that releases oxymorphone at acontrolled rate. Such hydrophilic materials include gums, celluloseethers, acrylic resins, and protein-derived materials. Suitablecellulose ethers include hydroxyalkyl celluloses and carboxyalkylcelluloses, especially hydroxyethyl cellulose (HEC), hydroxypropylcellulose (HPC), HPMC, and carboxy methylcellulose (CMC). Suitableacrylic resins include polymers and copolymers of acrylic acid,methacrylic acid, methyl acrylate and methyl methacrylate. Suitable gumsinclude heteropolysaccharide and homopolysaccharide gums, e.g., xanthan,tragacanth, acacia, karaya, alginates, agar, guar, hydroxypropyl guar,carrageenan, and locust bean gums.

Preferably, the controlled release tablet of the present invention isformed from (I) a hydrophilic material comprising (a) aheteropolysaccharide; or (b) a heteropolysaccharide and a cross-linkingagent capable of cross-linking said heteropolysaccharide; or (c) amixture of (a), (b) and a polysaccharide gum; and (II) an inertpharmaceutical filler comprising up to about 80% by weight of thetablet; and (III) oxymorphone.

The term “heteropolysaccharide” as used herein is defined as awater-soluble polysaccharide containing two or more kinds of sugarunits, the heteropolysaccharide having a branched or helicalconfiguration, and having excellent water-wicking properties and immensethickening properties.

A preferred heteropolysaccharide is xanthan gum, which is a highmolecular weight (>10⁶) heteropolysaccharide. Other preferredheteropolysaccharides include derivatives of xanthan gum, such asdeacylated xanthan gum, the carboxymethyl ether, and the propyleneglycol ester.

The cross linking agents used in the controlled release embodiment ofthe present invention which are capable of cross-linking with theheteropolysaccharide include homopolysaccharide gums such as thegalactomannans, i.e., polysaccharides which are composed solely ofmannose and galactose. Galactomannans which have higher proportions ofunsubstituted mannose regions have been found to achieve moreinteraction with the heteropolysaccharide. Locust bean gum, which has ahigher ratio of mannose to the galactose, is especially preferred ascompared to other galactomannans such as guar and hydroxypropyl guar.

Preferably, the ratio of heteropolysaccharide to homopolysaccharide isin the range of about 1:9 to about 9:1, preferably about 1:3 to about3:1. Most preferably, the ratio of xanthan gum to polysaccharidematerial (i.e., locust bean gum, etc.) is preferably about 1:1.

In addition to the hydrophilic material, the controlled release deliverysystem can also contain an inert pharmaceutical diluent such as amonosaccharide, a disaccharide, a polyhydric alcohol and mixturesthereof. The ratio of diluent to hydrophilic matrix-forming material isgenerally in the range of about 1:3 to about 3:1.

The controlled release properties of the controlled release embodimentof the present invention may be optimized when the ratio ofheteropolysaccharide gum to homopolysaccharide material is about 1:1,although heteropolysaccharide gum in an amount of from about 20 to about80% or more by weight of the heterodisperse polysaccharide materialprovides an acceptable slow release product. The combination of anyhomopolysaccharide gums known to produce a synergistic effect whenexposed to aqueous solutions may be used in accordance with the presentinvention. It is also possible that the type of synergism which ispresent with regard to the gum combination of the present inventioncould also occur between two homogeneous or two heteropolysaccharides.Other acceptable gelling agents which may be used in the presentinvention include those gelling agents well-known in the art. Examplesinclude vegetable gums such as alginates, carrageenan, pectin, guar gum,xanthan gum, modified starch, hydroxypropylmethylcellulose,methylcellulose, and other cellulosic materials such as sodiumcarboxymethylcellulose and hydroxypropyl cellulose. This list is notmeant to be exclusive.

The combination of xanthan gum with locust bean gum with or without theother homopolysaccharide gums is an especially preferred gelling agent.The chemistry of certain of the ingredients comprising the excipients ofthe present invention such as xanthan gum is such that the excipientsare considered to be self-buffering agents which are substantiallyinsensitive to the solubility of the medicament and likewise insensitiveto the pH changes along the length of the gastrointestinal tract.

The inert filler of the sustained release excipient preferably comprisesa pharmaceutically acceptable saccharide, including a monosaccharide, adisaccharide, or a polyhydric alcohol, and/or mixtures of any of theforegoing. Examples of suitable inert pharmaceutical fillers includesucrose, dextrose, lactose, microcrystalline cellulose, fructose,xylitol, sorbitol, mixtures thereof and the like. However, it ispreferred that a soluble pharmaceutical filler such as lactose,dextrose, sucrose, or mixtures thereof be used.

The cationic cross-linking agent which is optionally used in conjunctionwith the controlled release embodiment of the present invention may bemonovalent or multivalent metal cations. The preferred salts are theinorganic salts, including various alkali metal and/or alkaline earthmetal sulfates, chlorides, borates, bromides, citrates, acetates,lactates, etc. Specific examples of suitable cationic cross-linkingagents include calcium sulfate, sodium chloride, potassium sulfate,sodium carbonate, lithium chloride, tripotassium phosphate, sodiumborate, potassium bromide, potassium fluoride, sodium bicarbonate,calcium chloride, magnesium chloride, sodium citrate, sodium acetate,calcium lactate, magnesium sulfate and sodium fluoride. Multivalentmetal cations may also be utilized. However, the preferred cationiccross-linking agents are bivalent. Particularly preferred salts arecalcium sulfate and sodium chloride. The cationic cross-linking agentsof the present invention are added in an amount effective to obtain adesirable increased gel strength due to the cross-linking of the gellingagent (e.g., the heteropolysaccharide and homopolysaccharide gums). Inpreferred embodiments, the cationic cross-linking agent is included inthe sustained release excipient of the present invention in an amountfrom about 1 to about 20% by weight of the sustained release excipient,and in an amount about 0.5% to about 16% by weight of the final dosageform.

In the controlled release embodiments of the present invention, thesustained release excipient comprises from about 10 to about 99% byweight of a gelling agent comprising a heteropolysaccharide gum and ahomopolysaccharide gum, from about 1 to about 20% by weight of acationic crosslinking agent, and from about 0 to about 89% by weight ofan inert pharmaceutical diluent. In other embodiments, the sustainedrelease excipient comprises from about 10 to about 75% gelling agent,from about 2 to about 15% cationic crosslinking agent, and from about 30to about 75% inert diluent. In yet other embodiments, the sustainedrelease excipient comprises from about 30 to about 75% gelling agent,from about 5 to about 10% cationic cross-linking agent, and from about15 to about 65% inert diluent.

The sustained release excipient used in this embodiment of the presentinvention (with or without the optional cationic cross-linking agent)may be further modified by incorporation of a hydrophobic material whichslows the hydration of the gums without disrupting the hydrophilicmatrix. This is accomplished in preferred embodiments of the presentinvention by granulating the sustained release excipient with thesolution or dispersion of a hydrophobic material prior to theincorporation of the medicament. The hydrophobic polymer may be selectedfrom an alkylcellulose such as ethylcellulose, other hydrophobiccellulosic materials, polymers or copolymers derived from acrylic ormethacrylic acid esters, copolymers of acrylic and methacrylic acidesters, zein, waxes, shellac, hydrogenated vegetable oils, and any otherpharmaceutically acceptable hydrophobic material known to those skilledin the art. The amount of hydrophobic material incorporated into thesustained release excipient is that which is effective to slow thehydration of the gums without disrupting the hydrophilic matrix formedupon exposure to an environmental fluid. In certain preferredembodiments of the present invention, the hydrophobic material isincluded in the sustained release excipient in an amount from about 1 toabout 20% by weight. The solvent for the hydrophobic material may be anaqueous or organic solvent, or mixtures thereof.

Examples of commercially available alkylcelluloses are Aquacoat coating(aqueous dispersion of ethylcellulose available from FMC ofPhiladelphia, Pa.) and Surelease coating (aqueous dispersion ofethylcellulose available from Colorcon of West Point, Pa.). Examples ofcommercially available acrylic polymers suitable for use as thehydrophobic material include Eudragit RS and RL polymers (copolymers ofacrylic and methacrylic acid esters having a low content (e.g., 1:20 or1:40) of quaternary ammonium compounds available from Rohm America ofPiscataway, N.J.).

The controlled release matrix useful in the present invention may alsocontain a cationic cross-linking agent such as calcium sulfate in anamount sufficient to cross-link the gelling agent and increase the gelstrength, and an inert hydrophobic material such as ethyl cellulose inan amount sufficient to slow the hydration of the hydrophilic materialwithout disrupting it. Preferably, the controlled release deliverysystem is prepared as a pre-manufactured granulation.

It has now been discovered that the bioavailability ofcontrolled-release oxymorphone can be increased in patients with renalimpairment (impaired kidney function), and is especially so in patientswith moderately or severely impaired kidney function. Because of this,the oxymorphone levels in the blood of a patient with such renalimpairment are higher than the levels that would be seen in a healthypatient receiving the same dose. As such, in order to avoid potentialharmful effects, it is important to decrease the dose ofcontrolled-release oxymorphone in patients with renal impairment.

Since it is important that a patient or physician is aware that thebioavailability is increased so as to avoid possible issues in dosing,one embodiment of the invention comprises informing the patient or theprescribing physician that the bioavailability of oxymorphone may beincreased in some patients with renal impairment. Another embodiment ofthe invention comprises providing the patient or the patient'sprescribing physician with prescribing information comprisinginstructions for dosing the controlled release oxymorphone compositionto patients with renal impairment. For example, such instructions couldbe included in the labeling information, which can be the FDA-approvedlabeling, a package insert, or on the label itself. Other ways ofcommunicating with patients or physicians are also available and arecontemplated by the present invention. In another embodiment, theinstructions provided comprise instructions to administer the lowestavailable dose.

EXAMPLES Example 1

Two controlled release delivery systems are prepared by dry blendingxanthan gum, locust bean gum, calcium sulfate dehydrate, and dextrose ina high speed mixed/granulator for 3 minutes. A slurry is prepared bymixing ethyl cellulose with alcohol. While running choppers/impellers,the slurry is added to the dry blended mixture, and granulated foranother 3 minutes. The granulation is then dried to a LOD (loss ondrying) of less than about 10% by weight. The granulation is then milledusing 20 mesh screen. The relative quantities of the ingredients arelisted in the table below.

TABLE 1 Controlled Release Delivery System Formulation 1 Formulation 2Excipient (%) (%) Locust Bean Gum, FCC 25.0 30.0 Xanthan Gum, NF 25.030.0 Dextrose, USP 35.0 40.0 Calcium Sulfate Dihydrate, NF 10.0 0.0Ethylcellulose, NF  5.0 0.0 Alcohol, SD3A (Anhydrous) (10)¹  (20.0)¹Total 100.0  100.0

A series of tablets containing different amounts of oxymorphonehydrochloride were prepared using the controlled release deliveryFormulation 1 shown in Table 1. The quantities of ingredients per tabletare as listed in the following table.

TABLE 2 Sample Tablets of Differing Strengths Component Amount in Tablet(mg) Oxymorphone HCl, 5 10 20 40 80 USP (mg) Controlled release 160 160160 160 160 delivery system Silicified 20 20 20 20 20 microcrystallinecellulose, N.F. Sodium stearyl 2 2 2 2 2 fumarate, NF Total weight 187192 202 222 262 Opadry (colored) 7.48 7.68 8.08 8.88 10.48 Opadry(clear) 0.94 0.96 1.01 1.11 1.31

Examples 2, 3 and 4

Two batches of 20 mg tablets were prepared as described above, using thecontrolled release delivery system of Formulation 1. One batch wasformulated to provide relatively fast controlled release, the otherbatch was formulated to provide relatively slow controlled release.Compositions of the tablets are shown in the following table.

TABLE 3 Slow and Fast Release Compositions Example 2 Example 3 Example 4Ingredients Slow (mg) Fast (mg) Fast (mg) Oxymorphone HCl, USP 20 20 20Controlled Release Delivery System 360 160 160 SilicifiedMicrocrystalline Cellulose, 20 20 20 NF Sodium stearyl fumarate, NF 4 22 Total weight 404 202 202 Coating (color or clear) 12 12 9

The tablets of Examples 2, 3, and 4 were tested for in vitro releaserate according to USP Procedure Drug Release USP No. 23. Release rate isa critical variable in attempting to control the blood plasma levels ofoxymorphone and 6-hydroxyoxymorphone in a patient. Results are shown inthe following Table 4.

TABLE 4 Release Rates of Slow and Fast Release Tablets Example 2 Example3 Example 4 Time (hr) (Slow Release) (Fast Release) (Fast Release) 0.518.8 21.3 20.1 1 27.8 32.3 31.7 2 40.5 47.4 46.9 3 50.2 58.5 57.9 4 58.166.9 66.3 5 64.7 73.5 74.0 6 70.2 78.6 83.1 8 79.0 86.0 92.0 10 85.390.6 95.8 12 89.8 93.4 97.3 Clinical Studies

Three clinical studies were conducted to assess the bioavailability(rate and extent of absorption) of oxymorphone. Study 1 addressed therelative rates of absorption of controlled release (CR) oxymorphonetablets (of Examples 2 and 3) and oral oxymorphone solution in fastedpatients. Study 2 addressed the relative rates of absorption of CRoxymorphone tablets (of Examples 2 and 3) and oral oxymorphone solutionin fed patients. Study 3 addressed the relative rates of absorption ofCR oxymorphone tablets (of Example 4) and oral oxymorphone solution infed and fasted patients.

The blood plasma levels set forth herein as appropriate to achieve theobjects of the present invention are mean blood plasma levels. As anexample, if the blood plasma level of oxymorphone in a patient 12 hoursafter administration of a tablet is said to be at least 0.5 ng/ml, anyparticular individual may have lower blood plasma levels after 12 hours.However, the mean minimum concentration should meet the limitation setforth. To determine mean parameters, a study should be performed with aminimum of 8 adult subjects, in a manner acceptable for filing anapplication for drug approval with the US Food and Drug Administration.In cases where large fluctuations are found among patients, furthertesting may be necessary to accurately determine mean values.

For all studies, the following procedures were followed, unlessotherwise specified for a particular study.

The subjects were not to consume any alcohol-, caffeine-, orxanthine-containing foods or beverages for 24 hours prior to receivingstudy medication for each study period. Subjects were to be nicotine andtobacco free for at least 6 months prior to enrolling in the study. Inaddition, over-the-counter medications were prohibited 7 days prior todosing and during the study. Prescription medications were not allowed14 days prior to dosing and during the study.

Pharmacokinetic and Statistical Methods

The following pharmacokinetic parameters were computed from the plasmaoxymorphone concentration-time data:

AUC_((0-t)) Area under the drug concentration-time curve from time zeroto the time of the last quantifiable concentration (Ct), calculatedusing linear trapezoidal summation.

AUC_((0-inf)) Area under the drug concentration-time curve from timezero to infinity. AUC_((0-inf))=AUC_((0-t))+Ct/K_(el), where K_(el) isthe terminal elimination rate constant.

AUC₍₀₋₂₄₎ Partial area under the drug concentration-time curve from timezero to 24 hours.

C_(max) Maximum observed drug concentration.

T_(max) Time of the observed maximum drug concentration.

K_(el) Elimination rate constant based on the linear regression of theterminal linear portion of the LN (concentration) time curve.

Terminal elimination rate constants for use in the above calculationswere in turn computed using linear regression of a minimum of three timepoints, at least two of which were consecutive. K_(el) values for whichcorrelation coefficients were less than or equal to 0.8 were notreported in the pharmacokinetic parameter tables or included in thestatistical analysis. Thus AUC_((0-inf)) was also not reported in thesecases.

A parametric (normal-theory) general linear model was applied to each ofthe above parameters (excluding T_(max)), and the LN-transformedparameters C_(max), AUC₍₀₋₂₄₎, AUC_((0-t)), and AUC_((0-inf)).Initially, the analysis of variance (ANOVA) model included the followingfactors: treatment, sequence, subject within sequence, period, andcarryover effect. If carryover effect was not significant, it wasdropped from the model. The sequence effect was tested using the subjectwithin sequence mean square, and all other main effects were testedusing the residual error (error mean square).

Plasma oxymorphone concentrations were listed by subject at eachcollection time and summarized using descriptive statistics.Pharmacokinetic parameters were also listed by subject and summarizedusing descriptive statistics.

Study 1—Two Controlled Release Formulations; Fasted Patients

Healthy volunteers received a single oral dose of 20 mg CR oxymorphonetaken with 240 ml water after a 10-hour fast. Subjects received thetablets of Example 2 (Treatment 1A) or Example 3 (Treatment 1B). Furthersubjects were given a single oral dose of 10 mg/10 ml oxymorphonesolution in 180 ml apple juice followed with 60 ml water (Treatment 1C).The orally dosed solution was used to simulate an immediate release (IR)dose.

This study had a single-center, open-label, randomized, three-waycrossover design using fifteen subjects. Subjects were in a fasted statefollowing a 10-hour overnight fast. There was a 14-day washout intervalbetween the three dose administrations. The subjects were confined tothe clinic during each study period. Subjects receiving Treatment 1Cwere confined for 18 hours and subjects receiving Treatments 1A or 1Bwere confined for 48 hours after dosing. Ten-milliliter blood sampleswere collected during each study period at the 0 hour (predose), and at0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, 24, 28, 32,36, and 48 hours postdose for subjects receiving Treatment 1A or 1B and0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 7, 8, 10,12, 14, 16, and 18 hours post-dose. The mean plasma concentration ofoxymorphone versus time for each treatment across all subjects is shownin table 5.

TABLE 5 Mean Plasma Concentration vs. Time (ng/ml) Time (hr) Treatment1A Treatment 1B Treatment 1C 0 0.000  0.000  0.0000 0.25 0.9489 0.50.2941 0.4104 1.3016 0.75 1.3264 1 0.5016 0.7334 1.3046 1.25 1.2041 1.50.5951 0.8192 1.0813 1.75 0.9502 2 0.6328 0.7689 0.9055 2.5 0.7161 30.5743 0.7341 0.6689 4 0.5709 0.6647 0.4879 5 0.7656 0.9089 0.4184 60.7149 0.7782 0.3658 7 0.6334 0.6748 0.3464 8 0.5716 0.5890 0.2610 100.4834 0.5144 0.2028 12 0.7333 0.6801 0.2936 14 0.6271 0.6089 0.2083 160.4986 0.4567 0.1661 18 0.4008 0.3674 0.1368 20 0.3405 0.2970 24 0.27360.2270 28 0.3209 0.2805 32 0.2846 0.2272 36 0.2583 0.1903 48 0.09750.0792

The results are shown graphically in FIG. 5. In both Table 5 and FIG. 5,the results are normalized to a 20 mg dosage. The immediate releaseliquid of Treatment 1C shows a classical curve, with a high andrelatively narrow peak, followed by an exponential drop in plasmaconcentration. However, the controlled release oxymorphone tabletsexhibit triple peaks in blood plasma concentration. The first peakoccurs (on average) at around 3 hours. The second peak of the mean bloodplasma concentration is higher than the first, occurring around 6-7hours, on average).

Occasionally, in an individual, the first peak is higher than thesecond, although generally this is not the case. This makes it difficultto determine the time to maximum blood plasma concentration (T_(max))because if the first peak is higher than the second, maximum bloodplasma concentration (C_(max)) occurs much earlier (at around 3 hours)than in the usual case where the second peak is highest. Therefore, whenwe refer to the time to peak plasma concentration (T_(max)) unlessotherwise specified, we refer to the time to the second peak. Further,when reference is made to the second peak, we refer to the time or bloodplasma concentration at the point where the blood plasma concentrationbegins to drop the second time. Generally, where the first peak ishigher than the second, the difference in the maximum blood plasmaconcentration at the two peaks is small. Therefore, this difference (ifany) was ignored and the reported C_(max) was the true maximum bloodplasma concentration and not the concentration at the second peak.

TABLE 6 Pharmacokinetic Parameters of Plasma Oxymorphone for Study 1Treatment 1A Treatment 1B Treatment 1C Mean SD Mean SD Mean SD C_(max)0.8956 0.2983 1.0362 0.3080 2.9622 1.0999 T_(max) 7.03 4.10 4.89 3.440.928 0.398 AUC_((0-t)) 17.87 6.140 17.16 6.395 14.24 5.003AUC_((0-inf)) 19.87 6.382 18.96 6.908 16.99 5.830 T_(1/2el) 10.9 2.6811.4 2.88 6.96 4.61

Units: C_(max) in ng/ml, T_(max) in hours, AUC in ng*hr/ml, T_(1/2el) inhours.

Relative bioavailability determinations are set forth in Tables 7 and 8.For these calculations, AUC was normalized for all treatments to a 20 mgdose.

TABLE 7 Relative Bioavailability (F_(rel)) Determination Based onAUC_((0-inf)) F_(rel) (1A vs. 1C) F_(rel) (1B vs. 1C) F_(rel) (1A vs.1B) 1.193

 0.203 1.121

 0.211 1.108

 0.152

TABLE 8 Relative Bioavailability Determination Based on AUC₍₀₋₁₈₎F_(rel) (1A vs. 1C) F_(rel) (1B vs. 1C) F_(rel) (1A vs. 1B) 0.733

 0.098 0.783

 0.117 0.944

 0.110

Study 2—Two CR Formulations; Fed Patients

Healthy volunteers received a single oral dose of 20 mg CR oxymorphonetaken with 240 ml water in a fed state. Subjects received the tablets ofExample 2 (Treatment 2A) or Example 3 (Treatment 2B). Further subjectswere given a single oral dose of 10 mg/10 ml oxymorphone solution in 180ml apple juice followed with 60 ml water (Treatment 2C). The orallydosed solution was used to simulate an immediate release (IR) dose.

This study had a single-center, open-label, randomized, three-waycrossover design using fifteen subjects. The subjects were in a fedstate, after a 10-hour overnight fast followed by a standardized FDAhigh-fat breakfast. There was a 14-day washout interval between thethree dose administrations. The subjects were confined to the clinicduring each study period. Subjects receiving Treatment 2C were confinedfor 18 hours and subjects receiving Treatments 2A or 2B were confinedfor 48 hours after dosing. Ten-milliliter blood samples were collectedduring each study period at the 0 hour (predose), and at 0.5, 1, 1.5, 2,3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, 24, 28, 32, 36, and 48 hourspostdose for subjects receiving Treatment 2A or 2B and 0, 0.25, 0.5,0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, and18 hours postdose. The mean plasma concentration of oxymorphone versustime for each treatment across all subjects is shown in table 9.

TABLE 9 Mean Plasma Concentration vs. Time (ng/ml) Time (hr) Treatment2A Treatment 2B Treatment 2C 0 0.000 0.000 0.0000 0.25 1.263 0.5 0.396.0553 1.556 0.75 1.972 1 0.800 1.063 1.796 1.25 1.795 1.5 1.038 1.3191.637 1.75 1.467 2 1.269 1.414 1.454 2.5 1.331 3 1.328 1.540 1.320 41.132 1.378 1.011 5 1.291 1.609 0.731 6 1.033 1.242 0.518 7 0.941 0.9550.442 8 0.936 0.817 0.372 10 0.669 0.555 0.323 12 0.766 0.592 0.398 140.641 0.519 0.284 16 0.547 0.407 0.223 18 0.453 0.320 0.173 20 0.3820.280 24 0.315 0.254 28 0.352 0.319 32 0.304 0.237 36 0.252 0.207 480.104 0.077

The results are shown graphically in FIG. 6. Again, the results havebeen normalized to a 20 mg dosage. As with Study 1, the immediaterelease liquid of Treatment 2C shows a classical curve, with a high andrelatively narrow peak, followed by an exponential drop in plasmaconcentration, while the controlled release oxymorphone tablets exhibittriple peaks in blood plasma concentration. Thus, again when we refer tothe time to peak plasma concentration (T_(max)) unless otherwisespecified, we refer to the time to the second peak.

TABLE 10 Pharmacokinetic Parameters of Plasma Oxymorphone for Study 2Treatment 2A Treatment 2B Treatment 2C Mean SD Mean SD Mean SD C_(max)1.644 0.365 1.944 0.465 4.134 0.897 T_(max) 3.07 1.58 2.93 1.64 0.9470.313 AUC_((0-t)) 22.89 5.486 21.34 5.528 21.93 5.044 AUC_((0-inf))25.28 5.736 23.62 5.202 24.73 6.616 T_(1/2el) 12.8 3.87 11.0 3.51 5.012.02 Units: C_(max) in ng/ml, T_(max) in hours, AUC in ng*hr/ml,T_(1/2el) in hours.

In Table 10, the T_(max) has a large standard deviation due to the twocomparable peaks in blood plasma concentration. Relative bioavailabilitydeterminations are set forth in Tables 11 and 12.

TABLE 11 Relative Bioavailability Determination Based on AUC_((0-inf))F_(rel) (2A vs. 2C) F_(rel) (2B vs. 2C) F_(rel) (2A vs. 2B) 1.052

 0.187 0.949

 0.154 1.148

 0.250

TABLE 12 Relative bioavailability Determination Based on AUC₍₀₋₁₈₎F_(rel) (2A vs. 2C) F_(rel) (2B vs. 2C) F_(rel) (2A vs. 2B) 0.690

 0.105 0.694

 0.124 1.012

 0.175

As may be seen from tables 5 and 10 and FIGS. 1 and 2, the C_(max) forthe CR tablets (treatments 1A, 1B, 2A and 2B) is considerably lower, andthe T_(max) much higher than for the immediate release oxymorphone. Theblood plasma level of oxymorphone remains high well past the 8 (or eventhe 12) hour dosing interval desired for an effective controlled releasetablet.

Study 3—One Controlled Release Formulation; Fed and Fasted Patients

This study had a single-center, open-label, analytically blinded,randomized, four-way crossover design. Subjects randomized to Treatment3A and Treatment 3C, as described below, were in a fasted statefollowing a 10-hour overnight fast. Subjects randomized to Treatment 3Band Treatment 3D, as described below, were in the fed state, having hada high fat meal, completed ten minutes prior to dosing. There was a14-day washout interval between the four dose administrations. Thesubjects were confined to the clinic during each study period. Subjectsassigned to receive Treatment 3A and Treatment 3B were discharged fromthe clinic on Day 3 following the 48-hour procedures, and subjectsassigned to receive Treatment 3C and Treatment 3D were discharged fromthe clinic on Day 2 following the 36-hour procedures. On Day 1 of eachstudy period the subjects received one of four treatments:

Treatments 3A and 3B: Oxymorphone controlled release 20 mg tablets fromExample 3. Subjects randomized to Treatment 3A received a single oraldose of one 20 mg oxymorphone controlled release tablet taken with 240ml of water after a 10-hour fasting period. Subjects randomized toTreatment 3B received a single oral dose of one 20 mg oxymorphonecontrolled release tablet taken with 240 ml of water 10 minutes after astandardized high fat meal.

Treatments 3C and 3D: oxymorphone HCl solution, USP, 1.5 mg/ml 10 mlvials. Subjects randomized to Treatment 3C received a single oral doseof 10 mg (6.7 ml) oxymorphone solution taken with 240 ml of water aftera 10-hour fasting period. Subjects randomized to Treatment 3D received asingle oral dose of 10 mg (6.7 ml) oxymorphone solution taken with 240ml of water 10 minutes after a standardized high-fat meal.

A total of 28 male subjects were enrolled in the study, and 24 subjectscompleted the study. The mean age of the subjects was 27 years (range of19 through 38 years), the mean height of the subjects was 69.6 inches(range of 64.0 through 75.0 inches), and the mean weight of the subjectswas 169.0 pounds (range 117.0 through 202.0 pounds).

A total of 28 subjects received at least one treatment. Only subjectswho completed all 4 treatments were included in the summary statisticsand statistical analysis.

Blood samples (7 ml) were collected during each study period at the 0hour (predose), and at 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16,20, 24, 30, 36, and 48 hours post-dose (19 samples) for subjectsrandomized to Treatment 3A and Treatment 3B. Blood samples (7 ml) werecollected during each study period at the 0 hour (predose), and at 0.25,0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 20, and36 hours post-dose (21 samples) for subjects randomized to Treatment 3Cand Treatment 3D.

The mean oxymorphone plasma concentration versus time curves forTreatments 3A, 3B, 3C, and 3D are presented in FIG. 7. The results havebeen normalized to a 20 mg dosage. The data is contained in Table 13.The arithmetic means of the plasma oxymorphone pharmacokineticparameters and the statistics for all Treatments are summarized in Table14.

TABLE 13 Mean Plasma Concentration vs. Time (ng/ml) Treatment TreatmentTreatment Treatment Time (hr) 3A 3B 3C 3D 0 0.0084 0.0309 0.0558 0.00000.25 0.5074 0.9905 0.5 0.3853 0.3380 0.9634 1.0392 0.75 0.9753 1.3089 10.7710 0.7428 0.8777 1.3150 1.25 0.8171 1.2274 1.5 0.7931 1.0558 0.71091.1638 1.75 0.6357 1.0428 2 0.7370 1.0591 0.5851 0.9424 3 0.6879 0.98580.4991 0.7924 4 0.6491 0.9171 0.3830 0.7277 5 0.9312 1.4633 0.31110.6512 6 0.7613 1.0441 0.2650 0.4625 8 0.5259 0.7228 0.2038 0.2895 100.4161 0.5934 0.1768 0.2470 12 0.5212 0.5320 0.2275 0.2660 14 0.45270.4562 0.2081 0.2093 16 0.3924 0.3712 0.1747 0.1623 20 0.2736 0.30210.1246 0.1144 24 0.2966 0.2636 0.1022 0.1065 30 0.3460 0.3231 36 0.27280.2456 0.0841 0.0743 48 0.1263 0.1241

TABLE 14 Pharmacokinetic Parameters of Plasma Oxymorphone for Study 3Treatment 3B Treatment 3A Treatment 3C Treatment 3D Mean SD Mean SD MeanSD Mean SD C_(max) 1.7895 0.6531 1.1410 0.4537 2.2635 1.0008 3.27331.3169 T_(max) 5.65 9.39 5.57 7.14 0.978 1.14 1.11 7.768 AUC₍₀₋₂₄₎ 14.274.976 11.64 3.869 12.39 4.116 17.30 5.259 AUC_((0-t)) 19.89 6.408 17.718.471 14.53 4.909 19.20 6.030 AUC_((0-inf)) 21.29 6.559 19.29 5.02818.70 6.618 25.86 10.03 T_(1/2el) 12.0 3.64 12.3 3.99 16.2 11.4 20.619.3

The relative bioavailability calculations are summarized in tables 15and 16.

TABLE 15 Relative Bioavailability Determination Based on AUC_((0-inf))F_(rel) (3A vs. 3C) F_(rel) (3B vs. 3D) F_(rel) (3D vs. 3C) F_(rel) (3Bvs. 3A) 1.040 ± 0.1874 0.8863 ± 0.2569 1.368 ± 0.4328 1.169 ± 0.2041

TABLE 16 Relative bioavailability Determination Based on AUC₍₀₋₂₄₎F_(rel) (3A vs. 2C) F_(rel) (3B vs. 3D) F_(rel) (3D vs. 3C) F_(rel) (3Bvs. 3A) 0.9598 ± 0.2151 0.8344 ± 0.100 1.470 ± 0.3922 1.299 ± 0.4638

The objectives of this study were to assess the relative bioavailabilityof oxymorphone from oxymorphone controlled release (20 mg) compared tooxymorphone oral solution (10 mg) under both fasted and fed conditions,and to determine the effect of food on the bioavailability ofoxymorphone from the controlled release formulation, oxymorphone CR, andfrom the oral solution.

The presence of a high fat meal had a substantial effect on theoxymorphone C_(max), but less of an effect on oxymorphone AUC fromoxymorphone controlled release tablets. Least Squares (LS) mean C_(max)was 58% higher and LS mean AUC_((0-t)) and AUC_((0-inf)) were 18% higherfor the fed condition (Treatment B) compared to the fasted condition(Treatment A) based on LN-transformed data. This was consistent with therelative bioavailability determination from AUC_((0-inf)) since meanF_(rel) was 1.17. Mean T_(max) values were similar (approximately 5.6hours), and no significant difference in T_(max) was shown usingnonparametric analysis. Half value durations were significantlydifferent between the two treatments.

The effect of food on oxymorphone bioavailability from the oral solutionwas more pronounced, particularly in terms of AUC. LS mean C_(max) was50% higher and LS mean AUC_((0-t)) and AUC_((0-inf)) were 32-34% higherfor the fed condition (Treatment D) compared to the fasted condition(Treatment C) based on LN-transformed data. This was consistent with therelative bioavailability determination from AUC_((0-inf)) since meanF_(rel) was 1.37. Mean T_(max) (approximately 1 hour) was similar forthe two treatments and no significant difference was shown.

Under fasted conditions, oxymorphone controlled release 20 mg tabletsexhibited similar extent of oxymorphone availability compared to 10 mgoxymorphone oral solution normalized to a 20 mg dose (Treatment A versusTreatment C). From LN-transformed data, LS mean AUC_((0-t)) was 17%higher for oxymorphone CR, whereas LS mean AUC_((0-inf)) values werenearly equal (mean ratio=99%). Mean F_(rel) values calculated fromAUC_((0-inf)) and AUC₍₀₋₂₄₎, (1.0 and 0.96, respectively) also showedsimilar extent of oxymorphone availability between the two treatments.

As expected, there were differences in parameters reflecting rate ofabsorption. LS mean C_(max) was 49% lower for oxymorphone controlledrelease tablets compared to the dose-normalized oral solution, based onLN-transformed data. Half-value duration was significantly longer forthe controlled release formulation (means, 12 hours versus 2.5 hours).

Under fed conditions, oxymorphone availability from oxymorphonecontrolled release 20 mg was similar compared to 10 mg oxymorphone oralsolution normalized to a 20 mg dose (Treatment B versus Treatment D).From LN-transformed data, LS mean AUC_((0-inf)) was 12% lower foroxymorphone CR. Mean F_(rel) values calculated from AUC_((0-inf)) andAUC₍₀₋₂₄₎, (0.89 and 0.83 respectively) also showed similar extent ofoxymorphone availability from the tablet. As expected, there weredifferences in parameters reflecting rate of absorption. LS mean C_(max)was 46% lower for oxymorphone controlled release tablets compared to thedose-normalized oral solution, based on LN-transformed data. MeanT_(max) was 5.7 hours for the tablet compared to 1.1 hours for the oralsolution. Half-value duration was significantly longer for thecontrolled release formulation (means, 7.8 hours versus 3.1 hours).

The presence of a high fat meal did not appear to substantially affectthe availability of 6-hydroxyoxymorphone following administration ofoxymorphone controlled release tablets. LS mean ratios were 97% forAUC_((0-t)) and 91% for C_(max) (Treatment B versus A), based onLN-transformed data. This was consistent with the relativebioavailability determination from AUC₍₀₋₂₄₎, since mean F_(rel) was0.97. Mean T_(max) was later for the fed treatment compared to thefasted treatment (5.2 and 3.6 hours, respectively), and difference wassignificant.

Under fasted conditions, oxymorphone controlled release 20 mg tabletsexhibited similar availability of 6-hydroxyoxymorphone compared to 10 mgoxymorphone oral solution normalized to a 20 mg dose (Treatment A versusTreatment C). From LN-transformed data, LS mean ratio for AUC_((0-t))was 104.5%. Mean F_(rel) (0.83) calculated from AUC₍₀₋₂₄₎ also showedsimilar extent of oxymorphone availability between the two treatments.Mean T_(max) was 3.6 hours for the tablet compared to 0.88 for the oralsolution. Half-value duration was significantly longer for thecontrolled release formulation (means, 11 hours versus 2.2 hours).

Under fed conditions, availability of 6-hydroxyoxymorphone fromoxymorphone controlled release 20 mg was similar compared to 10 mgoxymorphone oral solution normalized to a 20 mg dose (Treatment B versusTreatment D). From LN-transformed data, LS mean AUC_((0-t)) was 14%higher for oxymorphone CR. Mean F_(rel) (0.87) calculated from AUC₍₀₋₂₄₎also indicated similar extent of availability between the treatments.Mean T_(max) was 5.2 hours for the tablet compared to 1.3 hour for theoral solution. Half-value duration was significantly longer for thecontrolled release formulation (means, 14 hours versus 3.9 hours).

The extent of oxymorphone availability from oxymorphone controlledrelease 20 mg tablets was similar under fed and fasted conditions sincethere was less than a 20% difference in LS mean AUC_((0-t)) andAUC_((0-inf)) values for each treatment, based on LN-transformed data.T_(max) was unaffected by food; however, LS mean C_(max) was increased58% in the presence of the high fat meal. Both rate and extent ofoxymorphone absorption from the oxymorphone oral solution were affectedby food since LS mean C_(max) and AUC values were increasedapproximately 50 and 30%, respectively. T_(max) was unaffected by food.Under both fed and fasted conditions, oxymorphone controlled releasetablets exhibited similar extent of oxymorphone availability compared tooxymorphone oral solution since there was less than a 20% difference inLS mean AUC(0-t) and AUC(0-inf) values for each treatment.

Bioavailability of 6-hydroxyoxymorphone following oxymorphone controlledrelease 20 mg tablets was also similar under fed and fasted conditionssince there was less than a 20% difference in LS mean C_(max) and AUCvalues for each treatment. T_(max) was later for the fed condition. Thepresence of food did not affect the extent of availability fromoxymorphone oral solution since LS mean AUC values were less than 20%different. However, C_(max) was decreased 35% in the presence of food.T_(max) was unaffected by food. Under both fed and fasted conditions,oxymorphone controlled release tablets exhibited similar extent ofavailability compared to oxymorphone oral solution since there was lessthan a 20% difference in LS mean AUC values for each treatment.

The mean 6-OH oxymorphone plasma concentration versus time curves forTreatments 3A, 3B, 3C, and 3D are presented in FIG. 8. The data iscontained in Table 17.

TABLE 17 Mean Plasma Concentration vs. Time (ng/ml) 6-HydroxyoxymorphoneTreatment Treatment Treatment Treatment Time (hr) 3A 3B 3C 3D 0 0.00690.0125 0.0741 0.0000 0.25 0.7258 0.4918 0.5 0.5080 0.1879 1.2933 0.59720.75 1.3217 0.7877 1 1.0233 0.4830 1.1072 0.8080 1.25 1.0069 0.7266 1.51.1062 0.7456 0.8494 0.7001 1.75 0.7511 0.6472 2 1.0351 0.7898 0.65540.5758 3 0.9143 0.7619 0.6196 0.5319 4 0.8522 0.7607 0.4822 0.5013 50.8848 0.8548 0.3875 0.4448 6 0.7101 0.7006 0.3160 0.3451 8 0.54210.5681 0.2525 0.2616 10 0.4770 0.5262 0.2361 0.2600 12 0.4509 0.44540.2329 0.2431 14 0.4190 0.4399 0.2411 0.2113 16 0.4321 0.4230 0.23850.2086 20 0.3956 0.4240 0.2234 0.1984 24 0.4526 0.4482 0.2210 0.2135 300.4499 0.4708 36 0.3587 0.3697 0.1834 0.1672 48 0.3023 0.3279

TABLE 18 Pharmacokinetic Parameters of Plasma 6-Hydroxyoxymorphone forStudy 3 Treatment 3A Treatment 3B Treatment 3C Treatment 3D Mean SD MeanSD Mean SD Mean SD C_(max) 1.2687 0.5792 1.1559 0.4848 1.5139 0.76160.9748 0.5160 T_(max) 3.61 7.17 5.20 9.52 0.880 0.738 1.30 1.04AUC_((0-t)) 22.47 10.16 22.01 10.77 10.52 4.117 9.550 4.281AUC_((0-inf)) 38.39 23.02 42.37 31.57 20.50 7.988 23.84 11.37 T_(1/2el)39.1 36.9 39.8 32.6 29.3 12.0 44.0 35.00

Study 4—Controlled Release 20 mg vs Immediate Release 10 mg

A study was conducted to compare the bioavailability andpharmacokinetics of controlled release and immediate release oxymorphonetablets under single-dose and multiple-dose (steady state) conditions.For the controlled release study, healthy volunteers received a singledose of a 20 mg controlled release oxymorphone table on the morning ofDay 1. Beginning on the morning of Day 3, the volunteers wereadministered a 20 mg controlled release oxymorphone tablet every 12hours through the morning dose of Day 9. For the immediate releasestudy, healthy volunteers received a single 10 mg dose of an immediaterelease oxymorphone tablet on the morning of Day 1. On the morning ofDay 3, additional 10 mg immediate release tablets were administeredevery six hours through the first two doses on Day 9.

FIG. 9 shows the average plasma concentrations of oxymorphone and6-hydroxyoxymorphone for all subjects after a single dose eithercontrolled release (CR) 20 mg or immediate release (IR) 10 mgoxymorphone. The data in the figure (as with the other relativeexperimental data herein) is normalized to a 20 mg dose. The immediaterelease tablet shows a classical curve, with a high, relatively narrowpeak followed by an exponential drop in plasma concentration. Thecontrolled release oxymorphone tablets show a lower peak with extendedmoderate levels of oxymorphone and 6-hydroxy oxymorphone. Table 19 showsthe levels of oxymorphone and 6-hydroxy oxymorphone from FIG. 9 intabular form.

TABLE 19 Mean Plasma Concentration (ng/ml) Oxymorphone6-Hydroxyoxymorphone Controlled Immediate Controlled Immediate ReleaseRelease Release Release Hour 20 mg 10 mg 20 mg 10 mg 0.00 0.00 0.00 0.000.00 0.25 0.22 1.08 0.14 0.73 0.50 0.59 1.69 0.45 1.22 1.00 0.77 1.190.53 0.79 1.50 0.84 0.91 0.53 0.57 2.00 0.87 0.75 0.60 0.47 3.00 0.830.52 0.55 0.34 4.00 0.73 0.37 0.53 0.27 5.00 0.94 0.36 0.46 0.23 6.000.81 0.28 0.41 0.18 8.00 0.73 0.20 0.37 0.14 10.0 0.60 0.19 0.35 0.1512.0 0.67 0.25 0.32 0.13 16.0 0.39 0.16 0.29 0.13 24.0 0.23 0.07 0.290.13 30.0 0.12 0.01 0.17 0.04 36.0 0.05 0.00 0.11 0.00 48.0 0.00 0.000.07 0.01

FIG. 10 shows the average plasma concentrations of oxymorphone and6-hydroxyoxymorphone for all subjects in the steady state test, fordoses of controlled release 20 mg tablets and immediate release 10 mgtablets of oxymorphone. The figure shows the plasma concentrations afterthe final controlled release tablet is given on Day 9, and the finalimmediate release tablet is given 12 hours thereafter. The steady stateadministration of the controlled release tablets clearly shows a steadymoderate level of oxymorphone ranging from just over 1 ng/ml to almost1.75 ng/ml over the course of a twelve hour period, where the immediaterelease tablet shows wide variations in blood plasma concentration.Table 20 shows the levels of oxymorphone and 6-hydroxyoxymorphone fromFIG. 10 in tabular form.

TABLE 20 Summary of Mean Plasma Concentration (ng/ml) Oxymorphone6-Hydroxyoxymorphone Controlled Immediate Controlled Immediate ReleaseRelease Release Release Day Hour 20 mg 10 mg 20 mg 10 mg 4 0.00 1.100.75 0.89 0.72 5 0.00 1.12 0.84 1.15 0.88 6 0.00 1.20 0.92 1.15 0.87 70.00 1.19 0.91 1.27 1.00 8 0.00 1.19 0.86 1.29 0.98 9 0.00 1.03 1.071.09 1.05 0.25 2.64 1.70 0.50 3.12 1.50 2.09 1.00 2.47 1.70 1.68 1.502.05 1.63 1.55 2.00 1.78 1.64 1.30 3.00 1.27 1.47 1.11 4.00 0.98 1.390.98 5.00 1.01 1.21 0.89 6.00 0.90 1.06 0.84 6.25 1.17 0.88 6.50 1.881.06 7.00 2.12 1.20 7.50 2.24 1.15 8.00 1.32 2.01 0.97 1.03 9.00 1.520.90 10.0 1.32 1.24 0.85 0.84 11.0 1.11 0.74 12.0 1.18 0.96 0.79 0.70

TABLE 21 Mean Single-Dose Pharmacokinetic Results Controlled Release 20mg Immediate Release 10 mg oxymor- 6-OH-oxymor- oxymor- 6-OH-oxymor-phone phone phone phone AUC(_(0-t)) 14.74 11.54 7.10 5.66 AUC(_(0-inf))15.33 16.40 7.73 8.45 C_(max)(ng/ml) 1.12 0.68 1.98 1.40 T_(max)(hr)5.00 2.00 0.50 0.50 T½(hr) 9.25 26.09 10.29 29.48

Parent 6-OH oxymorphone AUC_((o-t)) values were lower than the parentcompound after administration of either dosage form, but theAUC_((o-inf)) values are slightly higher due to the longer half-life forthe metabolite. This relationship was similar for both theimmediate-release (IR) and controlled release (CR) dosage forms. Asrepresented by the average plasma concentration graph, the CR dosageform has a significantly longer time to peak oxymorphone concentrationand a lower peak oxymorphone concentration. The 6-OH oxymorphone peakoccurred sooner than the parent peak following the CR dosage form, andsimultaneously with the parent peak following the IR dosage form.

It is important to note that while the present invention is describedand exemplified using 20 mg tablets, the invention may also be used withother strengths of tablets. In each strength, it is important to notehow a 20 mg tablet of the same composition (except for the change instrength) would act. The blood plasma levels and pain intensityinformation are provided for 20 mg tablets, however the presentinvention is also intended to encompass 5 to 80 mg controlled releasetablets. For this reason, the blood plasma level of oxymorphone or6-hydroxyoxymorphone in nanograms per milliliter of blood, per mgoxymorphone (ng/mg·ml) administered is measured. Thus at 0.02 ng/mg·ml,a 5 mg tablet should produce a minimum blood plasma concentration of 0.1ng/ml. A stronger tablet will produce a higher blood plasmaconcentration of active molecule, generally proportionally. Uponadministration of a higher dose tablet, for example 80 mg, the bloodplasma level of oxymorphone and 6-OH oxymorphone may more than quadruplecompared to a 20 mg dose, although conventional treatment of lowbioavailability substances would lead away from this conclusion. If thisis the case, it may be because the body can only process a limitedamount oxymorphone at one time. Once the bolus is processed, the bloodlevel of oxymorphone returns to a proportional level.

It is the knowledge that controlled release oxymorphone tablets arepossible to produce and effective to use, which is most important, madepossible with the high bioavailability of oxymorphone in a controlledrelease tablet. This also holds true for continuous periodicadministration of controlled release formulations. The intent of acontrolled release opioid formulation is the long-term management ofpain. Therefore, the performance of a composition when administeredperiodically (one to three times per day) over several days isimportant. In such a regime, the patient reaches a “steady state” wherecontinued administration will produce the same results, when measured byduration of pain relief and blood plasma levels of pharmaceutical. Sucha test is referred to as a “steady state” test and may require periodicadministration over an extended time period ranging from several days toa week or more. Of course, since a patient reaches steady state in sucha test, continuing the test for a longer time period should not affectthe results. Further, when testing blood plasma levels in such a test,if the time period for testing exceeds the interval between doses, it isimportant the regimen be stopped after the test is begun so thatobservations of change in blood level and pain relief may be madewithout a further dose affecting these parameters.

Study 5—Controlled Release 40 mg vs Immediate Release 4.times.10 mgunder Fed and Fasting Conditions

The objectives of this study were to assess the relative bioavailabilityof oxymorphone from oxymorphone controlled release (40 mg) compared tooxymorphone immediate release (4.times.10 mg) under both fasted and fedconditions, and to determine the effect of food on the bioavailabilityof oxymorphone from the controlled release formulation, oxymorphone CR,and from the immediate release formulation, oxymorphone IR.

This study had a single-center, open-label, analytically blinded,randomized, four-way crossover design. Subjects randomized to Treatment5A and Treatment 5C, as described below, were in a fasted statefollowing a 10-hour overnight fast. Subjects randomized to Treatment 5Band Treatment 5D, as described below, were in the fed state, having hada high fat meal, completed ten minutes prior to dosing. There was a14-day washout interval between the four dose administrations. Thesubjects were confined to the clinic during each study period. Subjectassigned to receive Treatment 5A and Treatment 5B were discharged fromthe clinic on Day 3 following the 48-hour procedures, and subjectsassigned to receive Treatment 5C and Treatment 5D were discharged fromthe clinic on Day 2 following the 36-hour procedures. On Day 1 of eachstudy period the subjects received one of four treatments:

Treatments 5A and 5B: Oxymorphone controlled release 40 mg tablets fromTable 2. Subjects randomized to Treatment 5A received a single oral doseof one 40 mg oxymorphone controlled release tablet taken with 240 ml ofwater after a 10-hour fasting period. Subjects randomized to Treatment5B received a single oral dose of one 40 mg oxymorphone controlledrelease tablet taken with 240 ml of water 10 minutes after astandardized high fat meal.

Treatments 5C and 5D: Immediate release tablet (IR) 4.times.10 mgOxymorphone. Subjects randomized to Treatment 5C received a single oraldose of 4.times.10 mg oxymorphone IR tablet taken with 240 ml of waterafter a 10-hour fasting period. Subjects randomized to Treatment 5Dreceived a single oral dose of 4.times.10 mg oxymorphone IR tablet takenwith 240 ml of water 10 minutes after a standardized high-fat meal.

A total of 28 male subjects were enrolled in the study, and 25 subjectscompleted the study. A total of 28 subjects received at least onetreatment. Only subjects who completed all 4 treatments were included inthe summary statistics and statistical analysis.

Blood samples (7 ml) were collected during each study period at the 0hour (predose), and at 0.25, 0.5, 0.75, 1.0, 1.5, 2, 3, 4, 5, 6, 8, 10,12, 24, 36, 48, 60, and 72 hours post-dose (19 samples) for subjectsrandomized to all Treatments.

The mean oxymorphone plasma concentration versus time is presented inTable 22. The arithmetic means of the plasma oxymorphone pharmacokineticparameters and the statistics for all Treatments are summarized in Table23.

TABLE 22 Mean Plasma Concentration vs. Time (ng/ml) Treatment TreatmentTreatment Treatment Time (hr) 5A 5B 5C 5D 0 0.00 0.00 0.00 0.00 0.250.47 0.22 3.34 1.79 0.50 1.68 0.97 7.28 6.59 0.75 1.92 1.90 6.60 9.49 12.09 2.61 6.03 9.91 1.5 2.18 3.48 4.67 8.76 2 2.18 3.65 3.68 7.29 3 2.002.86 2.34 4.93 4 1.78 2.45 1.65 3.11 5 1.86 2.37 1.48 2.19 6 1.67 2.021.28 1.71 8 1.25 1.46 0.92 1.28 10 1.11 1.17 0.78 1.09 12 1.34 1.21 1.041.24 24 0.55 0.47 0.40 0.44 36 0.21 0.20 0.16 0.18 48 0.06 0.05 0.040.05 60 0.03 0.01 0.01 0.01 72 0.00 0.00 0.00 0.00

TABLE 23 Pharmacokinetic Parameters of Plasma Oxymorphone for Study 5Treatment Treatment Treatment Treatment 5A 5B 5C 5D Mean SD Mean SD MeanSD Mean SD C_(max) 2.79 0.84 4.25 1.21 9.07 4.09 12.09 5.42 T_(max) 2.262.52 1.96 1.06 0.69 0.43 1.19 0.62 AUC_((0-t)) 35.70 10.58 38.20 11.0436.00 12.52 51.35 20.20 AUC_((0-inf)) 40.62 11.38 41.17 10.46 39.0412.44 54.10 20.26 T_(1/2el) 12.17 7.57 10.46 5.45 11.65 6.18 9.58 3.63

The relative bioavailability calculations are summarized in Tables 24and 25.

TABLE 24 Relative Bioavailability Determination Based on AUC_((0-inf))F_(rel) (5D vs. 5C) F_(rel) (5B vs. 5A) 1.3775 1.0220

TABLE 25 Relative bioavailability Determination Based on AUC₍₀₋₂₄₎F_(rel) (5D vs. 5C) F_(rel) (5B vs. 5A) 1.4681 1.0989

The mean 6-OH oxymorphone plasma concentration versus time is presentedin Table 26.

TABLE 26 Mean Plasma Concentration vs. Time (ng/ml) 6-HydroxyoxymorphoneTreatment Treatment Treatment Treatment Time (hr) 5A 5B 5C 5D 0 0.000.00 0.00 0.00 0.25 0.27 0.05 2.36 0.50 0.50 1.32 0.31 5.35 1.98 0.751.37 0.59 4.53 2.97 1 1.44 0.82 3.81 2.87 1.5 1.46 1.09 2.93 2.58 2 1.461.28 2.37 2.29 3 1.39 1.14 1.69 1.72 4 1.25 1.14 1.33 1.26 5 1.02 1.001.14 1.01 6 0.93 0.86 0.94 0.86 8 0.69 0.72 0.73 0.77 10 0.68 0.67 0.660.75 12 0.74 0.66 0.70 0.77 24 0.55 0.52 0.54 0.61 36 0.23 0.30 0.280.27 48 0.18 0.20 0.20 0.19 60 0.09 0.10 0.09 0.09 72 0.06 0.06 0.040.05

TABLE 27 Pharmacokinetic Parameters of Plasma 6-Hydroxyoxymorphone forStudy 5 Treatment Treatment Treatment Treatment 5A 5B 5C 5D Mean SD MeanSD Mean SD Mean SD C_(max) 1.88 0.69 1.59 0.63 6.41 3.61 3.79 1.49T_(max) 1.48 1.18 2.73 1.27 0.73 0.47 1.18 0.74 AUC_((0-t)) 28.22 10.8126.95 11.39 33.75 10.29 32.63 13.32 AUC_((0-inf)) 33.15 11.25 32.9810.68 37.63 17.01 36.54 13.79 T_(1/2el) 17.08 7.45 21.92 8.41 16.01 6.6816.21 7.42

Example 5 Study Objectives

The objective of this study was to determine the effect of renalimpairment on the pharmacokinetics and metabolism of oxymorphonefollowing a single oral dose of EN3202 (oxymorphone HClextended-release) tablets.

Methods

Clinical Study Design and Conduct

This study employed a single-dose, parallel-group study design in 24subjects with chronic renal insufficiency (8 with mild renal impairment,creatinine clearance=51-80 mL/min; 8 with moderate renal impairment,creatinine clearance=30-50 mL/min; and 8 with severe renal impairment,creatinine clearance <30 mL/min.) and 8 healthy controls with normalrenal function (creatinine clearance >80 mL/min). Attempts were made tomatch controls with the renal impaired patients with respect to age,gender, and weight. Each subject received a single 20 mg dose of EN3202(oxymorphone ER). The oxymorphone ER tablets administered were accordingto the now-available commercial formula of Opana® 20 mg strength, whichalso contains the inactive ingredients hypromellose, iron oxide black,methylparaben, propylene glycol, silicified microcrystalline cellulose,sodium stearyl fumarate, TIMERx®-N, titanium dioxide, triacetin, FD&Cblue No. 1, FD&C yellow No. 6, and FD&C yellow No. 10. Naltrexone (50mg) was administered on the evening prior to administration of theEN3202 dose. Plasma and urine were collected for 120 hours after theadministration of EN3202 to determine oxymorphone and metaboliteconcentrations. Study participants were housed in the clinical researchfacility during the treatment period, beginning on the evening prior toadministration of the test medication and extending until collection ofthe 120-hr blood sample and urine collection following doseadministration.

1.1.1 Overall Study Design

The study procedures are outlined in the following table (Table 28).

TABLE 28 Schedule of Study Evaluations Phase Screening Treatment PeriodVISIT NUMBER 1 2 DAY −21 −1 1 2 3 4 5 6 Medical/Medication History XInformed Consent X Assessment of Eligibility X X Physical Examination XX 12-lead Electrocardiogram X Clinical Laboratory Tests X X Serum HCG* XVital Signs X X X X X X X Body Weight X Clinic Check-in X ClinicDischarge X Urine Pregnancy Test* X Urine Drug Screen X X NaltrexoneDose X EN3202 Dose X Plasma Samples a a a a a a Urine Collection b b b bb b Assessment of AEs X X X X X X ^(a)Plasma sample times: 0 (pre-dose),0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 6.0, 8.0, 10.0, 12.0, 18.0, 24, 30,36, 48, 60, 72, 84, 96, 108, and 120 hours after dose administration.^(b)Urine collection times: 0 (pre-dose), 0-12, 12-24, 24-48, 48-72,72-96, 96-120 hours after dose administration. *For women ofchildbearing potential.

A series of screening evaluations were performed to determine whetherprospective study participants met the selection criteria for the trial.Screening evaluations were performed within a 21-day period prior toreceiving the study medication. Screening evaluations consisted of amedical history and review of systems, medication history, physicalexamination, 12-lead electrocardiogram, laboratory evaluations, andurine drug screen. A serum pregnancy test was obtained for women ofchildbearing potential. Screening tests for hepatitis and HIV infectionwere obtained only at the screening visit.

Creatinine clearance (Cl_(CR)) was estimated at screening using thefollowing Cockroft and Gault⁸ equation:

${Cl}_{CR} = {\frac{\left( {140 - {age}} \right) \cdot ({BW})}{\left( {72\; \times S_{CR}} \right)}\left( {{{for}\mspace{14mu}{males}};{{female} = {{male} \times 0.85}}} \right)}$

Where:

S_(CR)=serum creatinine (mg/dL)

BW=body weight in kg

Age=age in years

Urine drug screens were performed during screening and upon admission tothe clinic on the day prior to the treatment period. Urine pregnancytests were performed at check-in (when applicable). Each subject'scontinuing eligibility (e.g., inclusion and exclusion criteria,concomitant medications, etc.) was verified at check-in. Routine vitalsigns, including pulse, respiratory rate, blood pressure, andtemperature were obtained in conjunction with the screening physicalexamination, just prior to administration of the test medication, and at24, 48, 72, 96, and 120 hours after administration of the testmedication. Blood pressure and pulse were obtained with the subject inthe sitting position after sitting for 5 minutes. Laboratoryevaluations, physical examinations, and vital sign measurements wererepeated at the conclusion of the treatment period. Additional vitalsigns were to be obtained when clinically indicated.

Any significant abnormalities were to be fully investigated. Laboratoryresults with significantly abnormal values were to be repeated forverification. Additional tests and other evaluations required toestablish the significance or etiology of an abnormal result or tomonitor the course of an adverse event were to be obtained whenclinically indicated. In particular, if a clinically significantabnormal result was observed that was not resolved by the final studyvisit, repeat tests were to be performed to document resolution orstability of the abnormality. Any additional relevant data obtained bythe investigator during the course of this study were to be supplied tothe sponsor.

At the screening visit, subjects were informed not to take anymedications (prescription or OTC) until the study began. Renallyimpaired subjects were allowed to take approved prescribed concomitantmedications. The investigator informed each prospective subject of thenature of the study, explained the potential risks, and obtained writteninformed consent from the subject prior to performing any proceduresinvolving more than minimal risk and prior to the administration ofstudy medication.

Study participants reported to the clinic on the day prior to doseadministration (time specified by the investigator) and remained in theclinic until released by the investigator subsequent to obtaining the120-hour blood sample and urine collection. Naltrexone (50 mg) wasadministered on the evening prior to administration of EN3202 dose.While in the clinic, the subjects refrained from strenuous physicalactivity. Subjects fasted from approximately 22:00 on the evening priorto dose administration until four (4) hours after dose administration.At the end of the fasting period, the subjects received a standard dietfor the remainder of their time in the clinic. The subjects were not toreceive any xanthine-containing foods or beverages.

This was a single-dose trial. As a result, any subject who received thedose of test medication remained in the trial and completed all requiredtests and evaluations unless: a) the subject withdrew his or her consentfor further participation; b) the investigator determined that continuedparticipation in the trial placed the subject at unacceptable risk; orc) the investigator determined that the subject required medicaltreatment that could not be administered at the study facility.

Subjects who withdrew from the study prior to completion of the studyevaluations and blood samples scheduled for 72 hours following doseadministration could be replaced. Plasma samples could not be analyzedfor subjects who discontinued from the trial prior to collection of the72-hour blood sample. If a subject withdrew from the study, theinvestigator was to contact the monitor to discuss the necessity ofreplacement, and the decision was to be made prior to the analysis ofplasma samples. The replacement subject was to match the population ofthe subject that was withdrawn (i.e., healthy control, or renallyimpaired).

The date the subject withdrew from the study and the reason fordiscontinuation were to be recorded on the case report form. When asubject withdrew from the study (regardless of the reason), allevaluations required at the final study visit were to be performed.

Selection of the Study Population

A total of 34 subjects were enrolled in the trial, and 32 subjectscompleted the trial with 8 subjects in each of the following four (4)treatment groups:

Group Creatinine Clearance* Controls >80 mL/min Mild Renal Impairment 51to 80 mL/min Moderate Renal Impairment 30 to 50 mL/min Severe RenalImpairment <30 mL/min *Estimated using the method of Cockroft and Gault.A total of 36 subjects could be enrolled to allow for the completion of32 subjects.

To prevent the occurrence of acute abstinence syndrome resulting fromnaltrexone administration, the investigator carefully screened potentialstudy participants to ensure that no reasonable possibility of recent orprolonged opioid use or abuse existed. All potential study participantswere informed of the risks associated with attempting to withhold anyhistory of recent opioid use.

Subjects with Chronic Renal Insufficiency

Inclusion Criteria:

Twenty-six (26) male or female subjects with chronic renal insufficiencywere enrolled based on the following criteria:

-   -   Male or nonpregnant female 18 years of age or older. Female        patients of childbearing potential must have had a negative        serum β-hCG level consistent with nongravid state at the        pre-study screening visit and agreed to use an appropriate        method of contraception.    -   Diagnosis of chronic (≧6 months) renal insufficiency due to any        etiology that had been clinically stable (without episodes of        acute renal failure, fluctuating serum creatinine, or required        dialysis) for the last 2 months.    -   Estimated creatinine clearance within the range of 51 to 80        mL/min (8 subjects), 30 to 50 mL/min (8 subjects), or <30 mL/min        (8 subjects).    -   Body weights not less than 110 lb and within 30% of the        Metropolitan Life Insurance Company's standards dated 1983.    -   Able to communicate effectively with study personnel.    -   Hemoglobin ≧10 g/dL.    -   Platelet count >50,000 cells/□L.    -   Normal 12-lead electrocardiogram without any clinically        significant abnormalities of rate, rhythm, or conduction.    -   Adequately informed of the nature and risks of the study and        have given written informed consent prior to receiving study        medication.

Exclusion Criteria:

Any of the following conditions were cause for exclusion from the study:

-   -   Known hypersensitivity or allergy to oxymorphone or naltrexone.    -   Any disease or condition (medical or surgical) other than those        relating to their renal disease that might compromise the        hematologic, cardiovascular, pulmonary, hepatic,        gastrointestinal, or central nervous system.    -   Presence of significant abnormalities other than those related        to their renal insufficiency in pre-study clinical examination        or laboratory measurements.    -   Inadequately controlled hypertension, defined as diastolic blood        pressure >100 mmHg.    -   Positive screen for either Hepatitis B (Hepatitis B Surface        Antigen) or HIV.    -   Received an investigational drug within a period of 30 days        prior to enrollment in the study; consumption of alcohol within        72 hours prior to study initiation; or use of an unacceptable        concomitant medication.    -   Positive urine drug screen, including ethanol, cocaine, THC,        barbiturates, amphetamines, benzodiazepines, and opiates.    -   Any history of alcohol abuse, illicit drug use, significant        mental illness, physical dependence to any opioid, or any        history of drug abuse or addiction.    -   A history of difficulty with donating blood.    -   Received the study medication previously.

Healthy Control Subjects

Inclusion Criteria:

Eight (8) healthy controls subjects were enrolled based on the followingcriteria:

-   -   Male or nonpregnant female 18 years of age or older. Female        patients of childbearing potential must have had a negative        serum β-hCG level consistent with nongravid state at the        pre-study screening visit and agreed to use an appropriate        method of contraception.    -   Body weights not less than 110 lb and within 30% of the        Metropolitan Life Insurance Company's standards dated 1983.    -   Able to communicate effectively with the study personnel.    -   Estimated creatinine clearance >80 mL/min.    -   No significant disease or abnormal laboratory values as        determined by medical history, physical examination, or        laboratory evaluations conducted at the screening visit or on        admission to the clinic.    -   Normal 12-lead electrocardiogram without any clinically        significant abnormalities of rate, rhythm, or conduction.    -   Adequately informed of the nature and risks of the study and        have give written informed consent prior to receiving study        medication.

Exclusion Criteria:

Any of the following conditions are cause for exclusion from the study:

-   -   Known hypersensitivity or allergy to oxymorphone or naltrexone.    -   Any disease or condition (medical or surgical) that might        compromise the hematologic, cardiovascular, pulmonary, renal,        gastrointestinal, hepatic, or central nervous system, or other        conditions that might interfere with the absorption,        distribution, metabolism, or excretion of the study drug or        place the subject at increased risk.    -   Presence of abnormal laboratory values that are considered        clinically significant. In addition, no subject with liver        enzymes (SGOT or SGPT) above 1.25 times the upper limit of        normal, total bilirubin above the upper limit of normal, serum        creatinine above the upper limit of normal, or tests of        hematologic function (hemoglobin, hematocrit, white blood cells        or platelets) below the lower limit of normal were to be        admitted to the study.    -   Positive screen for either Hepatitis B (Hepatitis B Surface        Antigen) or HIV.    -   Received an investigational drug within a period of 30 days        prior to enrollment in the study. Any prescription drug therapy        within 2 weeks of initiation of the study. This exclusion was        extended to 4 weeks for any drugs known to affect hepatic drug        metabolism. No non-prescription (OTC) drugs were to be taken        within 24 hours of admission into the study. No consumption of        alcohol within 72 hours prior to study initiation.    -   Positive urine drug screen including ethanol, cocaine, THC,        barbiturates, amphetamines, benzodiazepines, and opiates.    -   Any history of alcohol abuse, illicit drug use, significant        mental illness, physical dependence to any opioid, or any        history of drug abuse or addiction.    -   A history of difficulty with donating blood.    -   Received the study medication previously.

Concomitant Medications

Healthy Control Subjects

-   -   Could not use concomitant prescription medications during the        study period beginning 2 weeks prior to the first dose (4 weeks        for any drug that might affect hepatic drug metabolism [see        Appendix F of the study protocol]).    -   Could not take OTC medications during the study beginning 24        hours prior to the administration of the test medication without        prior authorization of the investigator.    -   Could not consume alcoholic beverages during the study beginning        72 hours prior to the administration of the test medication.

Renally Impaired Subjects

-   -   Could continue to receive all medications chronically        administered for treatment or maintenance of their disease (such        medications must have been administered at a stable dosage for a        minimum of 2 weeks prior to entry into the trial).    -   Could not take OTC medications without prior authorization of        the investigator.    -   Could not consume alcoholic beverages during the study beginning        72 hours prior to administration of the first dose of study        medication.    -   Could receive additional medications, when medically necessary,        at the discretion of the investigator.

General Considerations

-   -   Opioid analgesics or opioid-containing medications (e.g., cough        suppressants containing opioids or dextromethorphan) were to be        prohibited beginning 2 weeks prior to the first dose and until        the subjects were discharged from the study.    -   Drugs that affect gastrointestinal motility were not to be        administered within 24 hours before or after administration of        the test medication. A laxative could be administered if        required, but the concurrent administration of any laxative was        prohibited within 24 hours before or after administration of the        test medication.    -   Medications with CNS-depressant effects were not to be        administered during the course of the study. If the renally        impaired subjects required the use of such medications, the        medication was to be administered at a stable dosage for a        minimum of 2 weeks prior to entry into the study and was to        remain at a constant dose throughout the study.

Study Medications

All study medications were supplied by the sponsor. Medications utilizedin this trial included the following:

-   -   EN3202 (oxymorphone HCl extended-release) tablets 20 mg (test        medication). The oxymorphone ER tablets administered were        according to the now-available commercial formula of Opana® 20        mg strength, which also contains the inactive ingredients        hypromellose, iron oxide black, methylparaben, propylene glycol,        silicified microcrystalline cellulose, sodium stearyl fumarate,        TIMERx®-N, titanium dioxide, triacetin, FD&C blue No. 1, FD&C        yellow No. 6, and FD&C yellow No. 10.    -   ReVia® (naltrexone HCl) tablets 50 mg (opioid antagonist)

In order to protect the subjects from potential opioid-related adverseevents, a single 50-mg dose of the opioid antagonist ReVia® (naltrexoneHCl) was administered at 20:00 the evening prior to administration oftest medication. A single 20-mg dose of oxymorphone HCl was administeredfollowing an overnight fast. Subjects continued fasting until four (4)hours after dose administration. The subjects remained in an uprightposture (sitting or standing) for 1 hour after dose administration. Alldoses were administered with 240 mL of water (room temperature), and thesubjects were instructed to drink all the water.

Randomization and Blinding

As participants in this study each received only a single dose ofEN3202, a randomization schedule was not required. This study was notsubject to blinding.

Safety Assessments

Each subject was carefully monitored for the development of any adverseexperiences. This information was obtained in the form of non-leadingquestions (e.g., “How are you feeling?”) and from signs and symptomsdetected during each examination, observations of the study personnel,or spontaneous reports from the subjects.

A standard 12-lead electrocardiogram was obtained at screening.Additional electrocardiograms were to be obtained if clinicallyindicated. A follow-up electrocardiogram was to be obtained if anysignificant abnormalities were detected after dose administration.

A complete physical examination was performed at the screening visit andat the conclusion of the treatment period. Routine vital signs,including pulse, respiratory rate, blood pressure, and temperature, wereobtained at the screening physical examination, just prior toadministration of the test medication, and at 24, 48, 72, 96, and 120hours after administration of the test medication. Blood pressure andpulse were obtained with the subject in a sitting position after sittingfor 5 minutes. Additional vital signs were to be obtained whenclinically indicated.

A complete series of laboratory evaluations (including blood chemistry,hematology and urinalysis) were obtained during the screening phase andalso at the conclusion of the study. Screening tests for hepatitis andHIV infection (and serum pregnancy tests when applicable) were obtainedonly at the screening visit. Urine drug screens were performed duringscreening and upon admission to the clinic on the day prior to thetreatment period. Urine pregnancy tests were performed at check-in (whenapplicable).

Any additional relevant data obtained by the investigator during thecourse of this study were to be supplied to the sponsor.

Analytical Methods

A total of four (4) validated LC/MS/MS methods were utilized to measurethe concentrations of oxymorphone, 6-OH-oxymorphone, andoxymorphone-3-glucuronide in plasma and urine samples. The methodsinclude: oxymorphone and 6-OH-oxymorphone in plasma (001005.01);oxymorphone-3-glucuronide in plasma (001107); oxymorphone and6-OH-oxymorphone in urine (001007.01), and oxymorphone-3-glucuronide inurine (001106). In all methods, the internal standards ared3-oxymorphone, d3-6-OH-oxymorphone, and d3-oxymorphone-3-glucuronidefor oxymorphone, 6-OH-oxymorphone, and oxymorphone-3-glucuronide,respectively. The methods for simultaneous determination of oxymorphoneand 6-OH-oxymorphone utilize liquid-liquid extraction of plasma orurine; the method for oxymorphone-3-glucuronide utilizes solid phaseextraction. Validation results are summarized in the following tables:

TABLE 29 Summary of Method Validation Results for Plasma AnalytesParameter OXM 6-OH-OXM OXM-3-G Standard Concentrations (ng/mL) 0.1, 0.2,0.5, 1, 0.1, 0.2, 0.5, 1, 5, 12.5, 25, 50, 5, 10, 18, 20 5, 10, 18, 20125, 200, 250 QC Concentrations (ng/mL) 0.3, 6, 14 0.3, 6, 14 15, 75,180 Linearity (mean r)   0.9994   0.9987   0.9982 Linear Range (ng/mL)0.1-20  0.1-20   5-250 LOQ (ng/mL) 0.1 0.1 5.0 Intra-day Precision (%CV)* 1.43-3.93 2.12-7.87 1.39-6.79 Intra-day Accuracy (% Actual)*94.33-96.56  98.17-102.56 101.00-105.31 Inter-day Precision (% CV)*2.86-7.77 3.83-7.74 3.85-5.53 Inter-day Accuracy (% Actual)* 97.31-99.36100.36-101.70  98.99-102.36 Recovery (%) 53.98 22.96 79.30 *precisionand accuracy results based on QC samples OXM = oxymorphone 6-OH-OXM =6-OH-oxymorphone OXM-3-G = oxymorphone-3-glucuronide

TABLE 30 Summary of Method Validation Results for Urine AnalytesParameter OXM 6-OH-OXM OXM-3-G Standard Concentrations (ng/mL) 1, 2.5,10, 25, 1, 2.5, 10, 25, 10, 25, 100, 250, 50, 100, 150, 200 50, 100,150, 200 500, 1000, 1500, 2000 QC Concentrations (ng/mL) 1.5, 60, 1401.5, 60, 140 30, 600, 1400 Linearity (mean r)   0.9994   0.9988   0.9990Linear Range (ng/mL)  1-200  1-200  10-2000 LOQ (ng/mL) 1.0 1.0 10.0 Intra-day Precision (% CV)* 2.00-7.26 3.04-4.73  4.63-6.02 Intra-dayAccuracy (% Actual)* 101.89-103.49 99.56-103.43  99.41-103.59 Inter-dayPrecision (% CV)* 3.18-7.04 3.73-7.86  4.55-6.17 Inter-day Accuracy (%Actual)*  98.92-102.33 98.70-100.65 97.50-99.26 Recovery (%) 62.92 67.1078.51 *precision and accuracy results based on QC samples OXM =oxymorphone 6-OH-OXM = 6-OH-oxymorphone OXM-3-G =oxymorphone-3-glucuronide

Pharmacokinetic and Statistical Methods

This was a parallel-group trial designed to enroll 24 subjects withmild, moderate, and severe renal impairment (8 subjects for each levelof impairment) and 8 healthy control subjects. Groups were matched forage, gender, and weight as closely as possible.

Samples of venous blood were obtained in 7 mL EDTA tubes just prior todose administration (time 0), and at 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0,6.0, 8.0, 10.0, 12.0, 18.0, 24.0, 30.0, 36.0, 48.0, 60.0, 72.0, 84.0,96.0, 108.0, and 120 hours after dose administration.

Urine samples were obtained for 120 hours after dose administration.Subjects were to be instructed to void just prior to administration ofthe test medication (time 0) and all urine was to be collected duringthe intervals of 0-12, 12-24, 24-48, 48-72, 72-96, and 96-120 hoursafter administration of the test medication. Each subject was to beinstructed to void at the end of each interval (so that each collectioninterval began with an empty bladder). The void prior to administrationof the test medication (time 0) served as the pre-dose blank and was notbe included in the collection container.

Calculation of Pharmacokinetic Variables

Plasma and urine pharmacokinetic variables were calculated from theconcentration data using standard, non-compartmental methods as outlinedin the following table.

TABLE 31 Definition of Pharmacokinetic Variables Variable DefinitionCmax Maximum plasma concentration; the highest concentration observedduring a dosage interval. Tmax The time that Cmax was observed. C_(t)The last measured plasma concentration; the last concentration above thelower LOQ following a dose. λ_(z) (Ke) The terminal elimination rateconstant; calculated using linear regression on the terminal portion ofthe Ln-concentration versus time curve. t½ Terminal eliminationhalf-life; calculated as 0.693/λz. AUCT Area under the concentrationversus time curve from time 0 to the last measured concentration(C_(t)); calculated using linear trapezoid rule. AUC Area under theconcentration versus time curve from time 0 to infinity; calculated asAUCT + C_(t)/λ_(z). CLo Clearance after oral administration; calculatedas dose/AUC. UER Urinary excretion rate; calculated as the amountexcreted during a collection interval (concentration in nmol ×volume)/the duration of collection (in hr). t½UER Elimination half-lifeestimated from urinary excretion rate; calculated using linearregression on the terminal portion of the Ln-UER versus time curve,where time is the mid-point of the collection interval.

Statistical Methods

All pharmacokinetic results are summarized using appropriate descriptivestatistics. Continuous variables were compared between renally impairedand control groups using appropriate parametric statistics. 90%confidence intervals were calculated for the differences or ratiosbetween the renally impaired and control groups. In addition, theassociation between oral clearance (and other pharmacokinetic variables)and the severity of renal insufficiency (based on creatinine clearance)was explored.

The frequency of adverse experiences (AEs) were tabulated by MedDRA termand body system. The incidence of AEs is compared across treatmentgroups using an appropriate non-parametric statistic. The maximumintensity and frequency of AEs are summarized by treatment group. Anew-onset AE is defined as an AE that was not present prior to treatmentwith study medication but appeared following treatment or was present attreatment initiation but worsened during treatment. An AE that waspresent at treatment initiation but resolved and then reappeared whilethe patient was on treatment is a new-onset AE (regardless of theintensity of the AE when the treatment was initiated).

All vital sign measurements are summarized by mean values and changesfrom baseline. Changes from baseline were analyzed across treatmentgroups using an appropriate parametric statistic.

Results

Disposition of Subjects

Thirty-four (34) participants, 8 healthy, 9 with mild renal impairment,8 with moderate renal impairment, and 9 with severe renal impairmentwere enrolled and received treatment; 32 completed the trial, and 2subjects discontinued the trial. Of the two subjects who discontinuedthe trial, one was in the mild renal impairment group (Subject 100), andone was in the severe renal impairment group (Subject 305). Bothsubjects discontinued due to adverse events.

The study population consisted of 22 men and 12 women ranging from 29 to87 years of age. As the severity of renal impairment tends to increasewith age, the renally impaired subjects were generally older, shorter,and weighed less than the healthy control subjects. The renally impairedsubjects were well matched for weight and height. (Table 32).

TABLE 32 Summary of Demographic Characteristics Mild Moderate SevereHealthy Impairment Impairment Impairment Controls Number 9 8 9 8 Males 35 7 7 Females 6 3 2 1 Age (years)^(a) 53.0 (3.83) 58.3 (5.68) 63.0(4.27)  41.9 (3.09) Height (in)^(a) 64.6 (1.32) 65.8 (0.65) 66.6 (1.53) 70.4 (1.44) Weight (lbs)^(a) 161.8 (11.68) 168.9 (9.40)  166.6 (8.18) 188.1 (8.11) Creatinine Clearance (mL/min)^(b) 63.1 (3.25) 42.2 (2.07)19.8 (1.46) 103.1 (5.79) ^(a)Mean (SE) ^(b)Mean (SE) creatinineclearance estimated by method of Cockroft and Gault (ref 8)

Results of Pharmacokinetic and Statistical Analyses

Pharmacokinetics of Oxymorphone and Metabolites in Plasma

The average plasma concentrations over time are shown in FIG. 11. Theaverage plasma concentrations of oxymorphone, 6-OH-oxymorphone, andoxymorphone-3-glucuronide followed a similar time course and the curvesare generally parallel. Examination of FIG. 1 reveals a clear differencein the plasma concentrations of oxymorphone-3-glucuronide across thefour treatment groups. The mean plasma oxymorphone concentrations insubjects with renal impairment generally exceeded those in the controlgroup during the first 12 hours after dose administration. As was thecase with the 3-glucuronide metabolite, the mean plasma oxymorphoneconcentrations generally followed the ordersevere>moderate>mild>control. There was less clear separation in mean6-OH-oxymorphone between the mild and moderately impaired groupsrelative to the healthy controls.

Mean (±SD) pharmacokinetic results for oxymorphone, 6-OH-oxymorphone,and oxymorphone-3-glucuronide are summarized by treatment group in Table33.

TABLE 33 Mean (SD) Plasma Pharmacokinetic Results (untransformed) MildModerate Severe Healthy Analyte/Variable Impairment ImpairmentImpairment Controls Oxymorphone AUC (ng · hr/mL) 21.68 (5.07) 27.93(8.34) 32.46 (19.12) 18.86 (9.39) AUCT (ng · hr/mL) 19.00 (6.26) 26.09(8.01) 29.72 (17.35) 15.79 (9.46) Cmax (ng/mL) 1.47 (0.54) 1.75 (0.59)2.04 (1.07) 1.16 (0.71) Tmax (hr)* 3.5 (1.0-12.0) 2.0 (0.5-5.0) 2.0(1.0-8.0) 3.5 (0.5-12.0) CLo (L/min.) 16.14 (3.94) 13.53 (6.52) 13.79(7.29) 22.07 (10.56) Ke (l/hr) 0.0660 (0.0300) 0.0733 (0.0162) 0.0652(0.0234) 0.0544 (0.0135) t½ (hr) 12.42 (5.10) 9.92 (2.45) 13.35 (9.45)13.46 (3.38) 6-OH-oxymorphone AUC (ng · hr/mL) 18.57 (6.91) 17.64 (6.12)32.04 (23.82) 19.76 (11.17) AUCT (ng · hr/mL) 14.26 (4.39) 11.70 (6.09)26.48 (21.36) 14.95 (10.58) Cmax (ng/mL) 0.99 (0.30) 0.76 (0.31) 0.99(0.55) 0.70 (0.34) Tmax (hr)* 1.5 (1.0-4.0) 2.5 (0.5-5.0) 2.0 (1.0-4.0)1.5 (0.5-18.0) Ke (l/hr) 0.0451 (0.0148) 0.0312 (0.0151) 0.0349 (0.0199)0.0449 (0.0344) t½ (hr) 18.04 (9.92) 27.82 (14.10) 26.53 (13.91) 22.20(10.76) Oxymorphone-3-glucuronide AUC (ng · hr/mL) 4468.6 (1352.0)8129.7 (3674.8) 23604.2 (11675.3) 2439.7 (597.7) AUCT (ng · hr/mL)4330.7 (1334.7) 7959.9 (3563.1) 22313.6 (9560.2) 2309.5 (532.6) Cmax(ng/mL) 280.2 (86.2) 359.7 (156.0) 547.7 (138.8) 170.1 (21.7) Tmax (hr)*3.5 (2.0-6.0) 4.5 (2.0-12.0) 11.0 (5.0-24.0) 3.0 (2.0-5.0) Ke (l/hr)0.0694 (0.0118) 0.0657 (0.0148) 0.0350 (0.0110) 0.0770 (0.0218) t½ (hr)10.23 (1.64) 11.10 (2.87) 22.09 (8.98) 9.53 (2.16) Source: Appendix 2.13*median (range)

The subjects with renal impairment had higher mean oxymorphone AUC andC_(max) values than the healthy controls (Table 33). The meanoxymorphone AUC ranged from 18.86 to 34.46 ng·hr/mL and C_(max) rangefrom 1.16 to 2.04 ng/mL in healthy controls and subjects with severerenal impairment, respectively. There do not appear to be anysubstantial differences in median T_(max) or in the mean eliminationrate constants for oxymorphone. Mean elimination half-life ranged from9.92 hours in subjects with moderate impairment to 13.46 hours inhealthy controls.

Mean oxymorphone-3-glucuronide AUC and C_(max) results weresubstantially higher in subjects with renal impairment relative to thehealthy controls. The mean oxymorphone-3-glucuronide AUC ranged from2440 to 23604 ng·hr/mL and C_(max) range from 170 to 548 ng/mL inhealthy controls and subjects with severe renal impairment,respectively. The differences in AUC and C_(max) also seemed to beassociated with a decrease in elimination rate. The mean eliminationhalf-life for oxymorphone-3-glucuronide increased from 9.5 hours inhealthy controls to 22.1 hours in subjects with severe renal impairment.

Pharmacokinetic differences between treatment groups are less clear for6-OH-oxymorphone. While subjects with severe renal impairment had highermean AUC values than healthy controls (32.04 vs. 19.76 ng·hr/mL,respectively), the mean AUC values in subjects with mild impairment(18.57 ng·hr/mL) and moderate impairment (17.64 ng·hr/mL) were lowerthan the controls.

The pharmacokinetic results for oxymorphone, 6-OH-oxymorphone, andoxymorphone-3-glucuronide were compared between treatment groupsfollowing ln-transformation (natural log). The AUC and Cmax results areshown in FIG. 12.

The mean bioavailability ratios (90% confidence intervals) foroxymorphone AUC are 1.2559 (0.8566-1.8414), 1.5722 (1.0723-2.3051), and1.6529 (1.1274-2.4234) relative to controls in subjects with mild,moderate, and severe renal impairment, respectively. The meanbioavailability ratios (90% confidence intervals) for oxymorphoneC_(max) are 1.3772 (0.9359-2.0265), 1.6494 (1.1209-2.4270), and 1.8042(1.2261-2.6549) relative to controls in subjects with mild, moderate,and severe renal impairment, respectively. As noted in FIG. 12, thelower 90% confidence limits for AUC and C_(max) in subjects with mildrenal impairment overlap 1.0, indicating that the observed differenceswere not statistically significant. The analysis of elimination rateconstants also did not reveal any significant differences betweensubjects with renal impairment relative to healthy controls. In fact,the mean plasma oxymorphone elimination rate constants in subjects withrenal impairment were higher than those in control subjects.

There were no statistically significant differences in mean AUC for6-OH-oxymorphone in subjects with mild, moderate, or severe renalimpairment relative to controls (FIG. 12). While the mean C_(max) wassignificantly higher than controls in subjects with mild renalimpairment (1.4818, 1.0067-2.1813), the relative bioavailability ratioswere lower in subjects with moderate or severe renal impairment.

The mean bioavailability ratios (90% confidence intervals) for6-OH-oxymorphone AUC are 0.9953 (0.6153-1.6100), 0.9445 (0.5839-1.5279),and 1.3862 (0.8569-2.2423) relative to controls in subjects with mild,moderate, and severe renal impairment, respectively.

The mean bioavailability ratios (90% confidence intervals) foroxymorphone-3-glucuronide Cmax are 1.5769 (1.2146-2.0473), 1.9830(1.5274-2.5745), and 3.1422 (2.4202-4.0795) relative to controls insubjects with mild, moderate, and severe renal impairment, respectively.

After conversion to molar units, the ratio of AUC values for6-OH-oxymorphone:oxymorphone and oxymorphone-3-glucuronide:oxymorphonewere calculated. The results are shown in FIG. 13.

Examination of FIG. 13 indicates a significant degree of overlap betweenthe four treatment groups for the ratio of 6-OH-oxymorphone:oxymorphone.The mean oxymorphone-3-glucuronide:oxymorphone ratios were 94.1, 132.3,191.4, and 505.6 in healthy controls and subjects with mild, moderate,and severe renal impairment, respectively.

Pharmacokinetics of Oxymorphone and Metabolites in Urine

Mean urinary excretion rates are plotted in FIG. 14. Urinary excretionof unchanged oxymorphone was essentially complete by the end of the 72to 96 hour collection interval for healthy controls and subjects withmild or moderate renal impairment. Examination of the urinary excretionrate plots (FIG. 14) indicates essentially parallel excretion ratecurves for oxymorphone in healthy controls and subjects with mild ormoderate renal impairment; subjects with severe renal impairmentexcreted oxymorphone at a slower rate. Mean urinary eliminationhalf-lives for oxymorphone were 12.5, 12.1, 13.9, and 21.0 hours inhealthy controls and subjects with mild, moderate, and severe renalimpairment, respectively.

Similar patterns of urinary excretion were observed for the 6-OH and3-glucuronide metabolites (FIG. 14); healthy controls and subjects withmild or moderate renal impairment had similar rates of excretion for thetwo metabolites, but subjects with severe renal impairment excreted themetabolites at a slower rate. Mean urinary elimination half-lives for6-OH-oxymorphone were 22.8, 19.6, 22.4, and 34.4 hours in healthycontrols and subjects with mild, moderate, and severe renal impairment,respectively. Mean urinary elimination half-lives foroxymorphone-3-glucuronide were 12.7, 9.8, 12.8, and 36.6 hours inhealthy controls and subjects with mild, moderate, and severe renalimpairment, respectively.

The cumulative amounts of oxymorphone, 6-OH-oxymorphone, andoxymorphone-3-glucuronide excreted in the urine are shown in FIG. 15,and the total amounts of oxymorphone and its metabolites recovered inthe urine are summarized in Table 34.

In all four treatment groups, urinary recovery of oxymorphone and6-OH-oxymorphone was greatest in the first 24 hours following doseadministration and was nearly complete by the end of the 48 hourcollection interval (FIG. 5). The mean amount oxymorphone excretedunchanged in the urine ranged from 0.38%-1.37% of the administered dosein subjects with severe and mild renal impairment, respectively (Table34). The mean percentage of the administered dose excreted in the urineas 6-OH-oxymorphone ranged from 0.16%-0.62% in subjects with severerenal impairment and healthy controls, respectively. Consistent with thelower mean urinary excretion rates, subjects with severe renalimpairment excreted less oxymorphone and 6-OH-oxymorphone in the urinethan subjects in the other three treatment groups.

Oxymorphone-3-glucuronide was the primary urinary metabolite in all fourtreatment groups. The mean percentage of the administered dose excretedin the urine as oxymorphone-3-glucuronide ranged from 37.16%-44.36% inhealthy controls and subjects with mild renal impairment, respectively(Table 34). While the recovery of oxymorphone-3-glucuronide wasessentially complete by 48 hours in healthy controls and subjects withmild or moderate renal impairment, excretion of this metabolite insubjects with severe renal impairment lagged behind the other groups(FIG. 15). The total amount of oxymorphone-3-glucuronide recovered inthe urine for subjects with severe renal impairment did not reach thelevels seen in healthy controls until the end of the 96 hour collectioninterval.

TABLE 34 Total Percent of Dose Recovered in Urine (0-120 hours) Mean(SD) Percent of Dose Recovered (0-120 hours) Compound Mild ModerateSevere Control Oxymorphone 1.37 (2.10) 0.66 (0.29) 0.38 (0.19) 0.77(0.36) 6-OH-oxymorphone 0.49 (0.15) 0.26 (0.14) 0.16 (0.11) 0.62 (0.28)Oxymorphone-3-glucuronide 44.36 (8.72)  38.87 (8.63)  38.35 (13.10)37.16 (14.94) Source: Appendix 2.26

The mean ratios of the amount of metabolite excreted in the urinerelative to the amount of unchanged oxymorphone excreted in the urineare summarized in Table 35.

TABLE 35 Mean (SD) Urinary Metabolite Ratios Mean (SD) Ratio ofMetabolite/Parent Excreted in Urine Compound Mild Moderate SevereControl 6-OH-OXM:OXM 0.73 (0.45) 0.41 (0.22) 0.47 (0.42) 0.85 (0.27)OXM-3-G:OXM 72.17 (48.36) 70.62 (37.69) 112.44 (40.45)  51.78 (16.89)6-OH-OXM = 6-OH-oxymorphone; OXM = oxymorphone, OXM-3-G =oxymorphone-3-glucuronide Source: Appendix 2.25

The ratio of 6-OH-oxymorphone:oxymorphone excreted in the urine wasreduced by approximately one-half in subjects with moderate or severerenal impairment relative to controls (Table 35), reflecting thereduction in urinary excretion of 6-OH-oxymorphone noted in Table 34.The large increase oxymorphone-3-glucuronide:oxymorphone ratio observedin patients with severe renal impairment primarily reflects the observedreduction in renal excretion of oxymorphone, since there is littledifference in the total amount of oxymorphone-3-glucuronide excreted inthe urine between subjects with severe renal impairment (38.35% of thedose) and controls (37.16% of the dose, Table 34).

Relationship between Oxymorphone Oral Clearance and Measures of RenalFunction

The potential association between plasma AUC and creatinine clearancewas explored using linear regression techniques and the results aresummarized in Table 36 and FIG. 16.

There was a weak positive association between oxymorphone oral clearanceand creatinine clearance, that while statistically significant, explainsvery little of the observed variation (Table 36).

TABLE 36 Correlation of Oxymorphone and Metabolite Plasma AUC withCreatinine Clearance Correlation Slope R-square P-value oxymorphone:CL/F vs. CL_(CR) 0.1229 0.2592 0.0029 oxymorphone: AUC vs. CL_(CR)−0.1852 0.2400 0.0044 6-OH-oxymorphone: AUC vs. CL_(CR) −0.1387 0.09770.0815 oxymorphone-3-glucuronide: −221.43 0.4976 0.0000 AUC vs. CL_(CR)oxymorphone: AUC/wt vs. CL_(CR) −0.0013 0.2898 0.0015 6-OH-oxymorphone:AUC/wt vs. CL_(CR) −0.0011 0.1222 0.0499 oxymorphone-3-glucuronide:−1.4140 0.4911 0.0000 AUC/wt vs. CL_(CR) CL_(CR) = creatinine clearanceAUC/wt = AUC normalized for body weight

As noted in Table 36, the only meaningful association appears to be foroxymorphone-3-glucuronide AUC and creatinine clearance. Examination ofFIG. 6, indicates that there is relatively little changes in AUC for the3-glucuronide metabolite until creatinine clearance falls below 50mL/min. For all three analytes, the most extreme values tend to beobserved when creatinine clearance is <30 mL/min.

Safety

Extent of Exposure

A total of 34 subjects received a single, oral, 20-mg dose of EN3202.The trial included 9 subjects with mild renal impairment, 8 subjectswith moderate renal impairment, 9 subjects with severe renal impairment,and 8 healthy controls. Thirty-two (32) subjects completed the trial; 2subjects (1 with mild and 1 with severe renal impairment) discontinuedthe trial due to adverse experiences. All 34 subjects also received asingle oral dose of naltrexone (50 mg) administered during the eveningprior to administration of the EN3202 dose.

Adverse Events

Twenty-five (25) subjects with renal impairment and three (3) healthycontrol subjects reported one or more adverse experiences (TABLE 37).

TABLE 37 Summary of Adverse Experiences (Event Reported by Two or MoreSubjects) Mild Moderate Severe Healthy Impairment Impairment ImpairmentControls Total Number of Subjects 9 8 9 8 Number with at least one AE  9(100.0%) 7 (87.5%)  9 (100.0%) 3 (37.5%) Headache NOS 5 (55.6%) 3(37.5%) 3 (33.3%) 2 (25.0%) Nausea 4 (44.4%) 0 4 (44.4%) 0 Feeling ofRelaxation 5 (55.6%) 0 2 (22.2%) 0 Dizziness (exc vertigo) 1 (11.1%) 0 3(33.3%) 1 (12.5%) Back Pain 2 (22.2%) 0 2 (22.2%) 0 Constipation 2(22.2%) 1 (12.5%) 1 (11.1%) 0 Vomiting NOS 3 (33.3%) 0 1 (11.1%) 0Arthralgia 1 (11.1%) 2 (25.0%) 0 0 Euphoric Mood 2 (22.2%) 0 0 1 (12.5%)Abdominal Pain NOS 1 (11.1%) 0 1 (11.1%) 0 Dyspepsia 1 (11.1%) 1 (12.5%)0 0 Feeling Hot 2 (22.2%) 0 0 0 Hypertension NOS 0 0 2 (22.2%) 0 Rigors1 (11.1%) 0 1 (11.1%) 0 Somnolence 0 0 2 (22.2%) 0

The majority of adverse experiences were mild in severity and occurredprimarily in subjects with renal impairment. None of the moderate orsevere adverse experiences occurred in the healthy control or moderaterenal impairment subject group. Four moderate adverse experiencesoccurred in subjects with mild renal impairment; five moderate adverseexperiences and one severe adverse experience occurred in subjects withsevere renal impairment. The only severe adverse experience was backpain.

Clinical Laboratory

Clinical laboratory tests were obtained at screening and at the end ofthe inpatient observation period (Day 5). One subject (305—severe renalimpairment group) had a clinically significant decline in renal functionduring the trial. Serum creatinine increased from 5.6 mg/dL at baselineto 7.9 mg/dL at end of the trial; BUN was essentially unchanged (74mg/dL at baseline and 92 mg/dL at end of study). This subject had nauseaand vomiting shortly after dose administration and was removed from thestudy due to the close proximity between the episode of vomiting and thetime of dose administration (in accordance with the study protocol). Thesubject remained in the clinic overnight and was discharged. The subjectwas contacted by the investigator to see his regular physician forfollow-up when the laboratory results were obtained. Follow-up resultsrevealed a serum creatinine of 6.0 mg/dL and BUN of 88 mg/dL.

A total of 25 subjects had one or more serum chemistry values outsidethe reference range at the end of the study evaluation. Except as notedabove, the observed changes were small and not clinically significant.

A total of 30 subjects had one or more hematology parameters outside thereference range at the end of the study evaluation. Most of the observedchanges were small, and none were clinically significant.

Vital Signs

Vital signs, including pulse, respiratory rate, blood pressure, andtemperature, were obtained during the screening physical examination,just prior to administration of the test medication, and at 24, 48, 72,96, and 120 hours after administration of the test medication.

No clinically significant changes were observed in pulse, respiratoryrate, blood pressure, or temperature. Subject 300 (a 66 year old malewith severe renal impairment who was previously treated forhypertension) had a blood pressure rate of 140/88 at screening. Duringthe trial, his blood pressure fluctuated between 190/98 and 220/110. Nomeaningful trends emerged during the 120 hour treatment period.

Physical Examination and ECG

Medical history data were collected at screening. Physical examinationswere performed at screening and at the end of the study. No clinicallysignificant findings were found. A 12-lead ECG was performed atscreening. No clinically significant readings were recorded.

Concomitant Medication

One healthy control subject was on birth control medication. A total of25 subjects out of 26 subjects with renal impairment received one ormore concomitant medications. Twenty-one (21) of the subjects with renalimpairment received medication for hypertension, ten (10) for diabetes,and eight (8) for renal conditions. The most common concomitantmedications administered were insulin for diabetes, lisinopril forhypertension, and furosemide for hypertension and renal conditions.

Summary of Analytical Performance

The study clinic shipped plasma and urine samples to the analyticalsite. The performance of the analytical methods during this period issummarized in the following tables.

TABLE 38 Summary of Analytical Performance for Plasma Analytes ParameterOXM 6-OH-OXM OXM-3-G Number of Runs 12 12 13 Linearity (mean r) 0.9980.998 0.999 Inter-day Precision 4.49-7.86% 5.73-10.00%   2.79-6.12% (%CV)* Inter-day Accuracy −5.08-−4.57% −4.31-−1.76%  −1.90-0.07% (%Actual)* *precision and accuracy results based on QC samples excludingdilutions OXM = oxymorphone 6-OH-OXM = 6-OH-oxymoiphone OXM-3-G =oxymorphone-3-glucuronide

TABLE 39 Summary of Analytical Performance for Urine Analytes ParameterOXM 6-OH-OXM OXM-3-G Number of Runs 4 3 2 Linearity (mean r) 0.999 0.9990.997 Inter-day Precision   2.73-5.12% 4.41-6.49%   0.42-4.94% (% CV)*Inter-day Accuracy −4.42-1.30% −4.13-−0.24% −6.85-9.23% (% Actual)**precision and accuracy results based on QC samples excluding dilutionsOXM = oxymorphone 6-OH-OXM = 6-OH-oxymorphone OXM-3-G =oxymorphone-3-glucuronide

Discussion

The mean bioavailability ratios (90% confidence intervals) foroxymorphone AUC are 1.2559 (0.8566-1.8414), 1.5722 (1.0723-2.3051), and1.6529 (1.1274-2.4234) relative to controls in subjects with mild,moderate, and severe renal impairment, respectively. There were nostatistically significant differences in mean AUC for 6-OH-oxymorphonein subjects with mild, moderate, or severe renal impairment relative tocontrols. The mean bioavailability ratios (90% confidence intervals) foroxymorphone-3-glucuronide AUC are 1.7960 (1.3071-2.4677), 3.1196(2.2704-4.2863), and 9.0701 (6.6013-12.462) relative to controls insubjects with mild, moderate, and severe renal impairment, respectively.

The log(natural log or ln) transformed AUC of oxymorphone of a patientwith moderately impaired kidney function may be about 1.05 to about 2.35times greater than that of a healthy patient, for example about 1.05times greater, about 1.10 times greater, about 1.15 times greater, about1.20 times greater, about 1.25 times greater, about 1.30 times greater,about 1.35 times greater, about 1.40 times greater, about 1.45 timesgreater, about 1.50 times greater, about 1.55 times greater, about 1.60times greater, about 1.65 times greater, about 1.70 times greater, about1.75 times greater, about 1.80 times greater, about 1.85 times greater,about 1.90 times greater, about 1.95 times greater, about 2.00 timesgreater, about 2.05 times greater, about 2.10 times greater, about 2.15times greater, about 2.20 times greater, about 2.25 times greater, about2.30 times greater, or about 2.35 times greater.

The log (natural log or ln) transformed AUC of oxymorphone of a patientwith severely impaired kidney function may be about 1.10 to about 2.45times greater than that of a healthy patient, for example about 1.10times greater, about 1.15 times greater, about 1.20 times greater, about1.25 times greater, about 1.30 times greater, about 1.35 times greater,about 1.40 times greater, about 1.45 times greater, about 1.50 timesgreater, about 1.55 times greater, about 1.60 times greater, about 1.65times greater, about 1.70 times greater, about 1.75 times greater, about1.80 times greater, about 1.85 times greater, about 1.90 times greater,about 1.95 times greater, about 2.00 times greater, about 2.05 timesgreater, about 2.10 times greater, about 2.15 times greater, about 2.20times greater, about 2.25 times greater, about 2.30 times greater, about2.35 times greater, about 2.40 times greater, or about 2.45 timesgreater.

The log (natural log or ln) transformed C_(max) of oxymorphone of apatient with moderately impaired kidney function may be about 1.10 toabout 2.45 times greater than that of a healthy patient, for exampleabout 1.10 times greater, about 1.15 times greater, about 1.20 timesgreater, about 1.25 times greater, about 1.30 times greater, about 1.35times greater, about 1.40 times greater, about 1.45 times greater, about1.50 times greater, about 1.55 times greater, about 1.60 times greater,about 1.65 times greater, about 1.70 times greater, about 1.75 timesgreater, about 1.80 times greater, about 1.85 times greater, about 1.90times greater, about 1.95 times greater, about 2.00 times greater, about2.05 times greater, about 2.10 times greater, about 2.15 times greater,about 2.20 times greater, about 2.25 times greater, about 2.30 timesgreater, about 2.35 times greater, about 2.40 times greater, or about2.45 times greater.

The log (natural log or ln) transformed C_(max) of oxymorphone of apatient with severely impaired kidney function may be about 1.20 toabout 2.70 times greater than that of a healthy patient, for exampleabout 1.20 times greater, about 1.25 times greater, about 1.30 timesgreater, about 1.35 times greater, about 1.40 times greater, about 1.45times greater, about 1.50 times greater, about 1.55 times greater, about1.60 times greater, about 1.65 times greater, about 1.70 times greater,about 1.75 times greater, about 1.80 times greater, about 1.85 timesgreater, about 1.90 times greater, about 1.95 times greater, about 2.00times greater, about 2.05 times greater, about 2.10 times greater, about2.15 times greater, about 2.20 times greater, about 2.25 times greater,about 2.30 times greater, about 2.35 times greater, about 2.40 timesgreater, about 2.45 times greater, about 2.50 times greater, about 2.55times greater, about 2.60 times greater, about 2.65 times greater, orabout 2.70 times greater.

All of the changes in plasma concentrations were accompanied byreductions in urinary excretion rates of percentage of the dose excretedin the urine. For example, the mean oxymorphone AUC was increased by anaverage of 1.7-fold and the mean percentage of the dose excreted in theurine as unchanged oxymorphone was reduced by approximately 50% insubjects with severe renal impairment relative to healthy controls.Decreasing levels of renal function had a greater effect on thecirculating concentrations of oxymorphone-3-glucuronide than on theplasma levels of oxymorphone. This is not unexpected since the3-glucuronide metabolite is the primary metabolite found in the urine.The mean urinary excretion rate half-life was 36.6 hours in subjectswith severe renal impairment and 12.7 hours in healthy controls.

There were weak, but statistically significant correlations betweenplasma AUC for oxymorphone and oxymorphone-3-glucuronide and creatinineclearance. The small r² values appear to be related, at least in part,to the fact that the relationship is not entirely linear. There isrelatively little change in plasma AUC for either oxymorphone oroxymorphone-3-glucuronide until the creatinine clearance falls below 50mL/min; and the highest AUC values were observed in subjects withcreatinine clearance values <30 mL/min.

CONCLUSION

Moderate-to-severe renal insufficiency was associated with a reductionin the renal excretion of oxymorphone and its principal urinarymetabolite, oxymorphone-3-glucuronide. These changes were associatedwith mean increases in plasma AUC values relative to healthy controls ofapproximately 1.8-fold and 9.7-fold for oxymorphone andoxymorphone-3-glucuronide, respectively in subjects with creatinineclearance values, 30 mL/min.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference there individually and specificallyindicated to be incorporated by reference were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of this disclosure (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted bycontext. The use of any and all examples, or exemplary language (e.g.,such as, preferred, preferably) provided herein, is intended merely tofurther illustrate the content of the disclosure and does not pose alimitation on the scope of the claims. No language in the specificationshould be construed as indicating any non-claimed element as essentialto the practice of the invention.

Alternative embodiments of the claimed invention are described herein,including the best mode known to the inventors for carrying out theclaimed invention. Of these, variations of the disclosed embodimentswill become apparent to those of ordinary skill in the art upon readingthe foregoing disclosure. The inventors expect skilled artisans toemploy such variations as appropriate, and the inventors intend for theinvention to be practiced otherwise than as specifically describedherein.

Accordingly, this invention includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above describedelements in all possible variations thereof is encompassed by theinvention unless otherwise indicated herein or otherwise clearlycontradicted by context.

The use of individual numerical values are stated as approximations asthough the values were preceded by the word “about” or “approximately.”Similarly, the numerical values in the various ranges specified in thisapplication, unless expressly indicated otherwise, are stated asapproximations as though the minimum and maximum values within thestated ranges were both preceded by the word “about” or “approximately.”In this manner, variations above and below the stated ranges can be usedto achieve substantially the same results as values within the ranges.As used herein, the terms “about” and “approximately” when referring toa numerical value shall have their plain and ordinary meanings to aperson of ordinary skill in the art to which the claimed subject matteris most closely related or the art relevant to the range or element atissue. The amount of broadening from the strict numerical boundarydepends upon many factors. For example, some of the factors which may beconsidered include the criticality of the element and/or the effect agiven amount of variation will have on the performance of the claimedsubject matter, as well as other considerations known to those of skillin the art. As used herein, the use of differing amounts of significantdigits for different numerical values is not meant to limit how the useof the words “about” or “approximately” will serve to broaden aparticular numerical value. Thus, as a general matter, “about” or“approximately” broaden the numerical value. Also, the disclosure ofranges is intended as a continuous range including every value betweenthe minimum and maximum values plus the broadening of the range affordedby the use of the term “about” or “approximately”. Thus, recitation ofranges of values herein are merely intended to serve as a shorthandmethod of referring individually to each separate value falling withinthe range, unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein.

What is claimed is:
 1. A method of treating pain in a renally impairedpatient, comprising the steps of: a. providing a solid oral controlledrelease dosage form, comprising: i. about 5 mg to about 80 mg ofoxymorphone or a pharmaceutically acceptable salt thereof as the soleactive ingredient; and ii. a controlled release matrix; b. measuring acreatinine clearance rate of the patient and determining it to be (a)less than about 30 ml/min, (b) about 30 mL/min to about 50 mL/min, (c)about 51 mL/min to about 80 mL/min, or (d) above about 80 mL/min; and c.orally administering to said patient, in dependence on which creatinineclearance rate is found, a lower dosage of the dosage form to providepain relief; wherein after said administration to said patient, theaverage AUC of oxymorphone over a 12-hour period is less than about 21ng·hr/mL.
 2. The method of claim 1, wherein the average AUC ofoxymorphone over a 12-hour period is less than about 20 ng·hr/mL.
 3. Themethod of claim 1, wherein the average AUC of oxymorphone over a 12-hourperiod is less than about 19 ng·hr/mL.
 4. A method of treating pain in arenally impaired patient, comprising the steps of: a. providing a solidoral controlled release dosage form, comprising: i. about 5 mg to about80 mg of oxymorphone or a pharmaceutically acceptable salt thereof asthe sole active ingredient; and ii. a controlled release matrix; b.measuring a creatinine clearance rate of the patient and determining itto be (a) less than about 30 mL/min, (b) about 30 mL/min to about 50mL/min, (c) about 51 mL/min to about 80 mL/min, or (d) above about 80ml/min; and c. orally administering to said patient, in dependence onwhich creatinine clearance rate is found, a lower dosage of the dosageform to provide pain relief; wherein after said administration to saidpatient, the Cmax of oxymorphone is less than about 1.4 ng/mL.
 5. Themethod of claim 4, wherein the average Cmax of oxymorphone is less thanabout 1.3 ng/mL.
 6. The method of claim 4, wherein the average Cmax ofoxymorphone is less than about 1.2 ng/mL.